Range report for high velocity test of Bullshops NOE 107s and Lotak lube

[DrB]

Bullshop had posted a thread a while back, linked below, that reported some high velocity (3650 fps) results with a 37 grain 22 caliber NOE 107 bullet out of a 221 Fireball, and lubed using his soft Lotak lube.

http://www.castboolits.gunloads.com/showthread.php?t=119026&highlight=high+velocity+usable

Bullshop's initial reported accuracy was so-so, but what captured my interest was the velocities he was reporting and the lack of lead fouling. Bullshop was kind enough to send me a small sample of bullets and a stick of his soft Lotak lube to experiment with. In exchange I promised Bullshop this range report with my results.

To cut to the chase, I found that in my k-hornet, I was able to achieve velocities of around 3200 fps average with Bullshop's NOE 107 bullets and Lotak soft lube. In my gun, I encountered no observable lead fouling after 80 rounds fired. The only apparent fouling was light carbon fouling that brushed/patched out quite easily. The best load I tested produced a measured five shot accuracy of just under 3 MOA, at 3217 fps with a standard deviation of 28 fps. The loads were tested at 25 and 100 yards, with no apparent change in the angle of dispersion as a function of range.

Rifle preparation:
I had previously used this rifle to shoot both jacketed and more recently, exclusively molybdenum disulfide coated jacketed bullets. Consequently, I wanted to be sure to remove as much copper fouling and/or any moly “pebbling” from the bores interior as possible prior to trying the cast bullets. I started out with a liberal spray of a penetrating oil, followed by about a half hour period of time for the oil to coat the bore, then bore brushing, a brake cleaner rinse and dry patches. This approach was repeated a couple of times, after which it still appeared to me some fouling was present. At this point, I utilized a patch wrapped bore brush coated with flitz polish and gave the bore fifty strokes, followed by penetrating oil, a brush, brake cleaner rinse, and dry patches till clean. After visual inspection which seemed to suggest the bore was free of fouling (as far as I could tell without better inspection tools) I then ran a lightly oiled patch through the bore.

Cast bullet processing:
I visually inspected the bullets Bullshop sent me, and found them to be quite nice – well filled out with sharp edges, and no visible defects. The bullets were from the same lot Bullshop had used in his earlier test from range scrap, and had not been measured for hardness. I checked the hardness and arrived at 23 BHN. (I used the camera methodology I have previously posted on for measuring hardness in combination with a Lee tester.)

Slugging the bore throat on my k-hornet, I found the bore to be about .225 groove to groove. The bullets I found to be .2252 to .2258 on their diameter. I didn't wish to decrease the as-cast diameter of the bullets at all, so I seated Hornady gas checks onto the bullets using a Lyman gas check seater with a RBCS lube-a-matic 2, such that the checks were just seated and crimped without sizing the bullet driving bands. Upon seating some checks, I noticed a couple of things.

First, there was a small crescent-shaped shiny spot of varying size on one side of the rear driving band where the bullet was apparently “kissing” the side of the die during check seating. Sometimes this shiny spot would extend up partially onto the forward driving band.

Second, upon fitting and playing with the checks I observed they were not seating flush on the bullet shank with initial finger seating. I measured the bullet shank and arrived at a dimension of .216-.217, and measured the Hornady check ID at the base and found the dimension was .214. Because of this mismatch in diameter, the checks would not seat flush with finger pressure.

To evaluate how badly they might be seating out of flush, I used a micrometer to measure the overall length of the bullets so I could find minimum and maximum OAL before and after check seating and estimate out-of-flatness for the check. What I found was that for this run of NOE 107 bullets, the nose of the bullets from the two mold halves were about .002 to .003 offset along the bullets axis of symmetry. I measure several bullets and got similar results, and confirmed that it appeared to be the result of a mold half offset by dragging my fingernail across the parting line on the nose from one side and then the other. As expected, it caught on the ~.002 ledge one way but not the other. Bases of the bullets appeared to be “perfectly” flat, having filled out to the sprue plate.

After seating gas checks, I found that typically there was not a variance in the minimum and maximum OAL as far as I could detect, so as near as I can tell the checks ended up square, at least to within a thousandth of an inch.

I then pan lubed the bullets with the soft Lotak in a pie pan/double boiler arrangement. While this mostly worked, the lube tended to want to pull out of the lube groove during cutting out and handling of the lubed bullets, and I did not find this to be an ideal method to apply the soft Lotak. While this formula is supposed to be “low-tackiness” (and perhaps was relatively so in stick form), after melting and resolidifying, the lube was both soft and quite tacky/sticky. Perhaps the melting/resolidifying altered the tack of the lube. Lotak would work well for hand application by smearing into the grooves, or by applying as intended without remelting the stick in the lubrisizer.

Brass processing:
The cases used for these loads are fireformed, annealed, and trimmed Remington Peters (RP headstamp) cases. The RP cases I have found have significantly greater case capacity (and thinner walls) than the Winchester WW headstamp cases. Most of the load variants were only neck-sized for about half of the length of the neck, such that the cartridge shoulder and bottom of the neck would align with the chamber and throat. A variant was tried in which the neck was unsized and the lubed bullet crimped into place after seating using a lee collet crimp die.

Loads Tried:
I tried several load variants ranging from 15 to 17 grains of Lil'Gun. Of course I do not recommend this load for others, etc., etc.... actually, without the right brass, a K-hornet or similar improved chamber, and fluidizing the charge I doubt others will even fit so much powder in a hornet case.

If anyone has an interest I'll be happy to post particulars on all the load variants and their results, but will omit it for now. Besides charge weight, the variants I ran also investigated bullet seating depth (out to engrave the lands and seated deeper with the lube groove inside the case neck), uncrimped vs. crimped with a lee collet crimp, and settled or unsettled powder charges fluidized with a headless ultrasonic toothbrush.

The brass were primed using Wolf small pistol primers. I have not done an exhaustive primer study, but use these wolf small pistol primers in my jacketed bullet loads in hornet with reasonable results, and so used them here as well.

Each charge was individually trickled and weighed on a powder scale. The heavier loads were settled in the case using a powder funnel and an ultrasonic toothbrush without the bristle head (which works great).

Bullets were seated in inside chamfered but unflared case necks using a Hornady concentric bullet seater. When crimped, the lee collet crimp die was set for one half turn of crimp.
http://castboolits.gunloads.com/imagehosting/154544e37b22d291a6.jpg

The best results were obtained from the following load:
RP case fireformed and neck sized for half of the neck length
Wolf Small Pistol primer
NOE 107 bullet of 23 BHN mystery alloy

Hornady gas check
Unsized (.2252-.2258)
Bullshop Lotak bullet lube

Lil'Gun charge of 17 grains settled with an ultrasonic toothbrush sans brush head (again, I do not necessarily recommend this load for others).
Bullet seated to just cover the lube groove, and crimped in place with a lee factory collet crimp die with crimp at ½ turn.

This load, as previously mentioned, produced 3.0 MOA in my rifle at 3217 fps average velocity, and 28 fps standard deviation.

Some possible sources of (in)accuracy:

The ~.002-.003 apparent offset in the mold halves produces a bullet that is slightly heavier on one side than the other.
The gas check shank was too large for the Hornady gas checks, a check that started out seated flush might end up more consistently flush (though I was unable to detect any out-of-flatness in the ones I spot-checked)
Wolf primers (a different primer might produce more consistent velocities, though I consider <1% SD variation to be pretty good)
Lotak lube buildup in the bullet seating die. I observed that bullet seating depth tended to become progressively deeper (measured variation was about .005 in OAL) due to the stickiness of the pan lubed Lotak bullets and the smears/pieces of Lotak stuck to bullet noses getting transferred to the die. A cleaner application of the soft Lotak such that the lube doesn't get into the concentric seating/nose portion of the die would ameliorate this. A more consistent bullet seating depth might tighten this up.
It's a ruger model 77. I've gotten less than ~1.2 MOA from this ruger with jacketed loads before, but it is probably not the most precise of rifles... off a bench, it does not appear to shoot better than I can see, hold, & squeeze even with the best jacketed loads I've developed.
Bullshop thinks an increase in the alloy hardness might have a beneficial effect at this velocity.


Fouling:
The first picture below was after firing twenty rounds, and shows a patch wrapped on a bore brush and pushed through once from chamber to muzzle. There was zero evidence of any gray colored or metallic fouling on the patch, after this one pass or after several passes through the barrel. The patch picked up a loose dry carbon fouling, which seemed to clean easily from the bore. The same fouling was observed after eighty shots, and cleaned up with several passes of a patched brush soaked in penetrating oil and followed with brake cleaner. No dull or streaky patches, or filling of the lands were observable after shooting – with a little cleaning, the bore was bright, shiny, with sharp dark rifling, and apparently fouling free.

After 20 rounds, patched brush passed from bore to muzzle
http://castboolits.gunloads.com/imagehosting/154544e37b22c8d743.jpg

Several scrubs of same patch...
http://castboolits.gunloads.com/imagehosting/154544e37b22cd0d51.jpg

After 80 rounds, patched brush scrubbed several strokes.
http://castboolits.gunloads.com/imagehosting/154544e37b25edf6c6.jpg

You can see the toolmarks from the rifling cutting process in this one... clean and crisp rifling.
http://castboolits.gunloads.com/imagehosting/154544e3739dfca3af.jpg

http://castboolits.gunloads.com/imagehosting/154544e3739e0160cd.jpg

Some carbon/powder fouling toward the chamber end of the barrel. This scrubbed/patched out easily.
http://castboolits.gunloads.com/imagehosting/154544e31e78458749.jpg


In summary, lead fouling at 3200 fps was a complete non-issue for these bullets and Lotak lube in my rifle over the course of 80 shots. There's some work to be done to improve accuracy, and I'd also like to try some different lube/bullet/load combinations to see where/when things fall apart. But really, getting these NOE 107 bullets with Lotak lube to go 3200 fps without lead fouling was completely painless.

Thanks, Bullshop, for the lube and bullets. I'm looking forward to playing with this combination more in the future.

Best regards,
DrB

[Bret4207]

Interesting. For the pressure you aren't using a super hard alloy, the design is pretty simple, a good lube of course helps. Kinda makes me wonder if it's just a matter or some sort of case capacity-bore ratio thing? I dunno. Keep at it!

[Larry Gibson]

DrB

Well done, a detailed excellent report. Consider if you backed off on the velocity and accuracy improves then the possible sources of inaccuracy you list are adversely affecting the bullets accuracy in flight as the velocity and RPM go up. If that is a 14" twist barrel you are pushing over the RPM threshold. If it is a 16" barrel twist you are on the ragged edge of the RPM threshold. Either way the 3 moa suggests something isn't flying right (pun intended).

Larry Gibson

[DrB]

DrB

Well done, a detailed excellent report. Consider if you backed off on the velocity and accuracy improves then the possible sources of inaccuracy you list are adversely affecting the bullets accuracy in flight as the velocity and RPM go up. If that is a 14" twist barrel you are pushing over the RPM threshold. If it is a 16" barrel twist you are on the ragged edge of the RPM threshold. Either way the 3 moa suggests something isn't flying right (pun intended).

Larry Gibson

Larry, thank you. I recalled your concern from prior discussion. Spin rate for the 3200 fps loads is running about 165,000 rpm. You had previously proposed, I believe, an rpm limit for this caliber of around 120,000-140,000 rpm? So it seems we are a fair bit above that here.

I'll add a post with moa vs. velocity. As mentioned, I did run lower powder charge variants. This load had both the highest velocity and the smallest grouping of those tried.

Our range is limited to 100 yds, so while I couldn't shoot these at greater ranges, I did shoot a target at 25 and 100. I was unable to determine a significant change in moa group size between the two ranges.

As near as I can tell, grouping here appears to be principally the result of barrel pointing at departure plus whatever lateral velocity component the bullets are getting at departure. I'm not seeing anything that looks like an "in-fight" effect.

Best regards,
DrB

[DrB]

Larry, here you go...

It would be interesting to collect more data for just two different velocity loads at 25 and 100 yards, and with more than five shots each. Note that the data points plotted represent five different load variants and five shots each. For each load variant, more than just powder charge/velocity were changed (crimp, seating depth, and powder settling were changed). A more correct way to analyze/plot these points would be using multiple linear regression, vs. just the x vs. y plots below. While I've done this before I'm still getting my software tools back in place to enable me to do it again... and really to have done it right I should have done a more formal experimental design that would have required more test points and work to collect/reduce the data.

http://castboolits.gunloads.com/imagehosting/154544e3835a6a8e21.png

In the above on the left, you can see that the group size generally trends down with increasing velocity (higher velocity is generally giving smaller groups, opposite to what you are suggesting should be expected). Note that the correlation coefficient (R^2) is poor, indicating that much of the variance in the data is not explained by the equation shown. In the plot on the right, you can see that there is generally a positive correlation between velocity standard deviation and increasing group size (group size goes up with increasing muzzle velocity variability).

While these plots don't show great fits to the data, again, keep in mind that there are other hidden variables in these loads that almost certainly account for some of the variability. Also, much of the poorness of the fit in both plots is a result of the Variant #4 data point, which I've removed below.

http://castboolits.gunloads.com/imagehosting/154544e3835a6eb0a7.png

In the above plots, you can see that there is actually a pretty good linear fit for both trends... it's a bit iffy given that there are only four data points to which the line is fitted (which reduces the statistical likelihood that the trend is real). Also, when you have one outlier among five data points and you eliminate it, that's a questionable action in as much as you are throwing away a fair bit of a limited data set...

Nonetheless, the data I have available are not consistent with the proposition that accuracy is decreasing as a function of increasing velocity -- if anything, the opposite appears to be a significant trend. It also appears that their is a correlation between the velocity variance and the group size, which makes sense if the principle source of inaccuracy is from the pointing of the muzzle at departure plus any lateral velocity component the bullet may be picking up at the time of departure of the bullet from the crown.

These data are also compatible with the jacketed data I have -- I suspect this is a trend principally related to the case capacity becoming filled, and the powder geometry/combustion/and velocity all becoming more consistent from shot-to-shot as a result.

Best regards,
DrB

[DrB]

Interesting. For the pressure you aren't using a super hard alloy, the design is pretty simple, a good lube of course helps. Kinda makes me wonder if it's just a matter or some sort of case capacity-bore ratio thing? I dunno. Keep at it!

Bret, I wonder if it may not be the combination of the smaller caliber and also the length/to bearing length of the bullet. Both of these things I think will tend to reduce the balloting/rifling loads on the bullet as it spins down the barrel as compared to a larger caliber/longer design.

RE case capacity vs. caliber -- Bullshop wondered something similar in his original post, and was using a 221 fireball for his shots. I really don't know. With a ball powder I wouldn't be surprised if you had a cloud/slug of powder following the bullet at least initially and acting kind of like (burning) cream of wheat. While I don't think it would seal the bore directly (it would produce hot gas at the base of the bullet), I do have an idea I'll be posting later on in the bullet base vs. accuracy sticky as to why a filler may help reduce gas leakage/cutting. A lightbulb went off while I was looking at one of 303Guy's recovered paper patched bullet pictures.

Best regards,
Caleb

[Bret4207]

FWIW- that boolit looks to me like a shrunken 311316 Lyman, one of the easiest boolits I've used to achieve high velocities in the 30 cals. Of course my "high velocities" were more like 23-2400 fps, but maybe it does have something to do with bearing length.

[DrB]

FWIW- that boolit looks to me like a shrunken 311316 Lyman, one of the easiest boolits I've used to achieve high velocities in the 30 cals. Of course my "high velocities" were more like 23-2400 fps, but maybe it does have something to do with bearing length.

Yes... Aside from the crimp groove it does, doesn't it? But it is 112 gr vs 37gr... do you have any suggestions for similar larger and smaller caliber bullet designs?

Found a picture of the 311316 below.

http://www.three-peaks.net/bullet_molds.htm

[Larry Gibson]

DrB

Once again, let me remind you and all others who think the RPM threshold is a "limit", it is not a limit. It is a threshold that may be moved up or down depending on the load and componants used. The RPM threshold generally runs in the 120 - 140,000 RPM range. You are indeed pushing it upward as I have and others have. Not a limit, ok?

"I suspect this is a trend principally related to the case capacity becoming filled, and the powder geometry/combustion/and velocity all becoming more consistent from shot-to-shot as a result."

I concur. Lil'Gun burns best at max charges. In the smaller capacity you are dealing with you may have hit case capacity before reaching the optimum pressure. Your charts/data is showing the groups tightening up as the pressure increases. What were the actual SD and ES for the progression of those loads? Switching to 2400, 4227, 4759, 4198 or 5744 might well bring better accuracy at a lower velocity or perhaps even as high as 3200 fps.

It is unfortunate also that you are restricted to 100 yards. The non linear dispersion difference between 25, 50 and 100 yards is not near as telling as between 100 and 200 yards.

Keep in mind that while a 5 shot group is "standard" fare these days it still is not really statistcally valid. A minimal sample of 8 is with 10 being preferred to get a 90% + assurance the data is valid.

Please do not misunderstand me, I am not being critical here at all. I am trying to help. A bump of the RPM threshold up to 165,000 is not that difficult if we find 3 moa accuracy to be acceptable. As I noted in Bullshop's thread, with such a rifle for varmint shooting 3 moa is not acceptable to me. It is however quite interesting and by no means and easy feat at 3200 fps with no leading.

Larry Gibson

[Bullshop]

Caleb that is a most excellent write up. Thank you for all the time and effort that you put into it.
Some of the other graph stuff is way over my head and I dont really even comprehend it.
I am pretty much just a dumb dumb trying to have fun shooting.
I am posting a picture of a couple targets I shot with the second batch of bullets I cast with the 107 mold and the 6/1 ww/monotype alloy and quenched. This is my favorite high velocity alloy.
The two targets at right are from the 221 fireball at 3650 fps from the 1/14" twist barrel. They should be somewhere near 196'000 rpm.
That is the best accuracy I have been able to get so far at this velocity.
The problem is I cant get it consistently and there are still the occasional wild flyer that goes 5" to 6" out of the group.
The target at left is very interesting also. I wanted to see if I could get any kind of accuracy from a much longer boolit in the same rpm range.
That target was fired using the NOE 72 grain rn boolit from a 22 BR with a 1/9" twist. The velocity was 2460 fps so should have an rpm of about 196'800 so is exceeding the short boolit by a little bit.
If you look close you can see the order that the shots were fired in. The #5 shot went out about 2" to the right so I fired a sixth shot that went right back into the group. I cant say why #5 went out but figure it was a bad boolit. I dont weigh or sort them other than to look for defects when size/lubing them.
Anyway there is a new batch of boolits from the 6/1 alloy on the way to you. It did seem to improve my average with the 221 at least a little.
OH BTW yesterday I had to dispatch a sick chicken. Since it was in a safe position about 40 yards from my shop I thought I would use the fireball with the 107/3650 fps load. It did just exactly what you would think it would do, it blew chicken all over the place. A most excellent load for ridding the garden of pests!
Oh and I forgot to mention that these are 100 yard targets and the coin on the plate is a nickle.

http://castboolits.gunloads.com/imagehosting/1414e38c8bddcb32.jpg

[DrB]

Once again, let me remind you and all others who think the RPM threshold is a "limit", it is not a limit. It is a threshold that may be moved up or down depending on the load and componants used. The RPM threshold generally runs in the 120 - 140,000 RPM range. You are indeed pushing it upward as I have and others have. Not a limit, ok?


Larry, I think maybe I got in on this conversation late, because I really doubt I understand what your RPM threshold theory is. It seems to me your theory either makes a testable prediction or it does not?

If your theory just boils down to "you can spin a bullet too fast" I don't see how that is very interesting. Yes, it is obviously true (all solids have ultimate strengths), but if you aren't going to say something empirically or analytically about when it becomes true, or why, how is it useful to anyone? I'm not trying to question your observations here in any way, I'm just wondering about how you have chosen to interpret them?

As I thought I understood it, you were making two testable assertions:

accuracy would go to pot beyond 120k-140k rpm for a 22 caliber, and
the mechanism causing accuracy to go to pot was (some unspecified mechanism) occuring in freeflight (external ballistics) and would result in a non-constant angular dispersion (nonlinear increase in group size).


Accuracy improving with increasing RPM, and constant angular dispersion over range are both observations in my results that are not supportive of your predictions as I understood them.
This load is above your previously stated "rpm threshold" of 140k rpm
it exhibits no measured increase in MOA as a function of range
MOA in fact is decreasing with increasing RPM.


You also have asserted that the rpm threshold would be lower for smaller caliber projectiles, as the force due to a given rpm would be greater, and I demonstrated to you that this was the opposite of what was physically true -- that for a given rpm, acceleration, force, and stress would all go up with increasing caliber. A table, a plot -- something illustrating the proposed variation of your "threshold" as a function of caliber, etc., would be helpful.



What were the actual SD and ES for the progression of those loads? Switching to 2400, 4227, 4759, 4198 or 5744 might well bring better accuracy at a lower velocity or perhaps even as high as 3200 fps.


SD (Standard Deviation) was noted in the previously posted chart on the right. I shouldn't have used the word "Variance" in the independent axis label, as I should have said variability. Typo.

RE alternative powders, perhaps, but as far as I've seen to date, folks don't report as high velocities with powders other than lil'gun in the hornet. At maximum loads, they also typically report pressure signs -- which I have yet to encounter even using pistol primers at these maximum velocity loads. Maybe someone has relevant experience in the hornet they could share that would suggest otherwise. I'd be interested to hear loads.



It is unfortunate also that you are restricted to 100 yards. The non linear dispersion difference between 25, 50 and 100 yards is not near as telling as between 100 and 200 yards.


OK, but Larry -- there is no observed dispersion in the data. I am open to taking further data at 25 and 100 yards, but when do you propose it would be enough? Also, if I kept going out to greater and greater ranges, how would you suggest I distinguish between the effects of air convection/turbulence and this bullet spin rate/range dependent phenomenon of yours? To discount the effects of near ground air speed over the course of the bullet from shot to shot, the effect would have to be fairly dramatic, and the wind obviously pretty calm, right? Well, nothing dramatic was apparent here out to 100 yards.... just saying.

Perhaps you can offer some plots from your load experiments of constant shot number group sizes as a function of range? The shape of those might help us here with discussing what this effect of yours should look like in the present data, if actually present.



Keep in mind that while a 5 shot group is "standard" fare these days it still is not really statistcally valid. A minimal sample of 8 is with 10 being preferred to get a 90% + assurance the data is valid.


Larry, your statement is incorrect (and vague). The statistical adequacy of the population sample size is dependent upon both the nature of the population(s) and the statistical inference that is being made.

For example, here's an example of how your statement is untrue. If I wish to make the statistical inference that one population's mean was greater than another's, and the real mean value of one population was a million with a standard deviation of one, and the real mean value of a second population was one, with a standard deviation of one, and I took a sample size of three from each population, computed the mean of each, etc., are you really arguing that if I repeated the statistical test using samples of three from each population a large number of times, I wouldn't come to the correct decision more than 90% of the time (or less than 99.9999...%)? Or that the computed theoretical statistical confidence from a single test of a sample of three from each wouldn't be WAY in excess of 90% for just three samples each (I could run that number for you, but I think the answer is intuitively obvious as I've laid it out)?

There is not a fixed "right" sample size for a statistical inference. The necessary size depends on the inference and the populations being sampled... it also depends on the model.



Please do not misunderstand me, I am not being critical here at all. I am trying to help. A bump of the RPM threshold up to 165,000 is not that difficult if we find 3 moa accuracy to be acceptable. As I noted in Bullshop's thread, with such a rifle for varmint shooting 3 moa is not acceptable to me. It is however quite interesting and by no means and easy feat at 3200 fps with no leading.


Thanks Larry -- I do appreciate your feedback, and love your wealth of observations and personal experience. The range report of yours I've read so far was very well written.

I really think a compilation/plot of your data that you used to deduce your rpm theory would be helpful if you ever have the opportunity and inclination to put one together.

Best regards,
DrB

[DrB]

Caleb that is a most excellent write up. Thank you for all the time and effort that you put into it.
Some of the other graph stuff is way over my head and I dont really even comprehend it.
I am pretty much just a dumb dumb trying to have fun shooting.
I am posting a picture of a couple targets I shot with the second batch of bullets I cast with the 107 mold and the 6/1 ww/monotype alloy and quenched. This is my favorite high velocity alloy.
The two targets at right are from the 221 fireball at 3650 fps from the 1/14" twist barrel. They should be somewhere near 196'000 rpm.
That is the best accuracy I have been able to get so far at this velocity.
The problem is I cant get it consistently and there are still the occasional wild flyer that goes 5" to 6" out of the group.
The target at left is very interesting also. I wanted to see if I could get any kind of accuracy from a much longer boolit in the same rpm range.
That target was fired using the NOE 72 grain rn boolit from a 22 BR with a 1/9" twist. The velocity was 2460 fps so should have an rpm of about 196'800 so is exceeding the short boolit by a little bit.
If you look close you can see the order that the shots were fired in. The #5 shot went out about 2" to the right so I fired a sixth shot that went right back into the group. I cant say why #5 went out but figure it was a bad boolit. I dont weigh or sort them other than to look for defects when size/lubing them.
Anyway there is a new batch of boolits from the 6/1 alloy on the way to you. It did seem to improve my average with the 221 at least a little.
OH BTW yesterday I had to dispatch a sick chicken. Since it was in a safe position about 40 yards from my shop I thought I would use the fireball with the 107/3650 fps load. It did just exactly what you would think it would do, it blew chicken all over the place. A most excellent load for ridding the garden of pests!
Oh and I forgot to mention that these are 100 yard targets and the coin on the plate is a nickle.

http://castboolits.gunloads.com/imagehosting/1414e38c8bddcb32.jpg

Dan, neat results!

I look forward to playing with the new batch of bullets.

Lay off putting yourself down... (unless all this sandbagging is how you win at poker :razz: ). I was surprised when you called the reduction in velocity I saw going from jacketed to cast and I saw the numbers I was getting. I haven't gone back to my jacketed data to calculate it, but your prediction of about 200 fps reduction with the change to cast is pretty darn close. (btw, this reduction also makes me wonder if perhaps a source of the velocity variability is the initial confinement of the charge. Seems like the in-bore resistance should be less with cast, and yet the velocity is lower with slightly more powder -- maybe the powder isn't getting ignited as completely? A hotter primer may be in order).

Anyway, so far, the products of yours I've tried (bullplate lube, your NOE 107 cast bullets, and your lotak) have each done exactly what they were billed to do. From everything I've read about cast bullets over 1800-2400 fps and fouling, I really expected at 3200 fps there to be some major trial and tribulation, tears, yelling, and gnashing of teeth with fouling, but there was no grief whatsoever with any of the load variants I tried. Slick as a whistle for eighty shots, as far as I can tell, with just a cursory dry scrubbing at 20 rounds fired. :shock: There are plenty of overeducated folks out here (I definitely include myself :)) who don't have as good a track record as I've seen from you so far.

I've got a NOE 107 load coming from Al. I'm interested to compare the grouping of my few remaining first BS run bullets, the new ones you've sent, and a run from the new mold. That mold half offset on the first batch makes me wonder how much of the group size might be due to bullet asymmetry, and how much the group size may change with the new run? Have you ever tried clocking your bullets so the same mold half was up to see if it changed your grouping?

Also, regarding terminal effect, I haven't tested it yet. With my 35 grain V-maxes at ~3400 fps, they make a neat round hole in the front of a full milk jug, shoot the top about 15 yards into the air, burst the jug about flat, but make not a mark at all on the back face of the jug. I suspect these 37 grain NOEs at 23 BHN and 3200 fps will penetrate to make a hole on the back side, but with similar hydrostatic effect. What do you think? You've already shot some jugs, haven't you?

Best regards,
DrB

[Bret4207]

Yes... Aside from the crimp groove it does, doesn't it? But it is 112 gr vs 37gr... do you have any suggestions for similar larger and smaller caliber bullet designs?

Found a picture of the 311316 below.

http://www.three-peaks.net/bullet_molds.htm

Nope, but maybe some bright engineer type could figure out the diameter/length ratio or whatever the number is called and add in the CG and ballistic coefficient and a mess of other numbers to try and come up with a number that might lead to something. Darn sure I can't do it.

I will note that IME the blunt RN or FN Loverin designs were always easy to get shooting at high speeds. Don't know if that helps or not.

[DrB]

Nope, but maybe some bright engineer type could figure out the diameter/length ratio or whatever the number is called and add in the CG and ballistic coefficient and a mess of other numbers to try and come up with a number that might lead to something. Darn sure I can't do it.

I will note that IME the blunt RN or FN Loverin designs were always easy to get shooting at high speeds. Don't know if that helps or not.

L/D would be fineness ratio, I believe.

To come up with a similarity parameter it would be nice to know the shape of what works and doesn't... Seems to me there're so many constraints at play, it won't be just one.

[Bullshop]

We have shot some quart bottles and yes there is always an exit hole in the back but you have to be good with puzzles to find it. The water show is very impressive.
I have not yet tried to determine the percent of meplate to caliber of the little 107 but it will be high as the meplate is the largest of all my 22 cal molds.
I feel I am getting good enough results to call my 221 a good garden gun. For shots not exceeding 100 yards a chuck even if hit on the fringes will be messes up badly. I doubt there will be any cripples to crawl off and suffer.

[Larry Gibson]

Larry, I think maybe I got in on this conversation late, because I really doubt I understand what your RPM threshold theory is. It seems to me your theory either makes a testable prediction or it does not?

If your theory just boils down to "you can spin a bullet too fast" I don't see how that is very interesting. Yes, it is obviously true (all solids have ultimate strengths), but if you aren't going to say something empirically or analytically about when it becomes true, or why, how is it useful to anyone? I'm not trying to question your observations here in any way, I'm just wondering about how you have chosen to interpret them?

DrB

I’m not exactly sure what many of your points are here. It is obvious you do not understand the RPM threshold or how it works. I have explained this many times on this forum. Also I suggest you study ballistics a little more, seems some confusion there also, especially in exterior ballistics. No criticism there, just pointing out that some of your arguments are not correct in that respect.

As I thought I understood it, you were making two testable assertions:
1. accuracy would go to pot beyond 120k-140k rpm for a 22 caliber, and
2. the mechanism causing accuracy to go to pot was (some unspecified mechanism) occuring in freeflight (external ballistics) and would result in a non-constant angular dispersion (nonlinear increase in group size).

You are making erroneous assumptions of ascertations you acredit to me. In our previous conversations discussing this I said it was more likely for a smaller caliber to be more difficult to shoot accurately at high velocity/RPM. I did not say “accuracy would go to pot” as a certainty. I have always said (as I said in this thread) that the RPM threshold could be raised or lowered with any caliber, including the .224.

The “mechanism” is not “unspecified” as I have explained it before. For your edification I will quote it again;

“the bullet is unbalanced or becomes unbalance due to obturation in the bore during acceleration. The unbalanced bullet is forced to conform while in the barrel and its center of mass is revolving around it's geometric center. When the bullet is free of the barrel's constraint, it will move in the direction that its mass center had at the point of release. After exiting the muzzle, the geometric center will begin to revolve about the center of mass and it will depart at an angle to the bore (line of departure). At 54,000 RPM to 250,000 RPM, depending on velocity and twist, the centrifugal force can be tremendous. It will result in an outward or radial acceleration from the intended flight path (line of departure) and will try to get the bullet to rotate in a constantly growing helix.”

Accuracy improving with increasing RPM, and constant angular dispersion over range are both observations in my results that are not supportive of your predictions as I understood them.
1. This load is above your previously stated "rpm threshold" of 140k rpm
2. it exhibits no measured increase in MOA as a function of range
3. MOA in fact is decreasing with increasing RPM.
They were not supportive of your own misunderstanding of the RPM threshold. If the bullet is not exceeding the RPM threshold it does not apply. Accuracy improving as pressure builds so the powder burns consistently and efficiently is a common and well known fact of reloading when working up loads. Most often there is a direct correlation, given a proper and well made bullet, between improved SD/ES and accuracy. The adverse affects of the exceeding the RPM threshold when the bullet begins a helical spiral in flight occur after the RPM threshold is exceeded, not before.


You also have asserted that the rpm threshold would be lower for smaller caliber projectiles, as the force due to a given rpm would be greater, and I demonstrated to you that this was the opposite of what was physically true -- that for a given rpm, acceleration, force, and stress would all go up with increasing caliber.

That is correct and I agreed with you but you are misunderstanding and again acrediting me with something not quite what I said. If the defect is the same in relation to the mass of the bullet then what you say is indeed correct. If, however, the defect is simply the same (say a .3 gr defect) then the ratio of the defect to the bullets mass gets much larger in a smaller caliber bullet. The adverse affect of that larger ratio makes the smaller caliber more difficult to get past the RPM threshold. If we are weighing bullets and we use a +/- .2 gr that +/- .2 gr is a much larger variance to a 35 or 55 gr .225 cast bullet than it is to a 180 – 200 gr .30 cal cast bullet or a 500 gr .45 cal cast bullet. A better understanding of ballistics will also demonstrate that where that imbalance is located (in front of the center of pressure, center of gravity, in line with the center of form, for & aft center and the center of spin) can and does have an adverse affect on nutations and yawing of the bullet in flight. Those nutations and yawing also cause inaccuracies which are why we shoot groups instead of all bullets following exactly the same flight path. Nutations and yawing are present before during and after the RPM threshold.

If there was a previous misunderstanding of what I said I hope this clears it up.

A table, a plot -- something illustrating the proposed variation of your "threshold" as a function of caliber, etc., would be helpful.
Quote:
What were the actual SD and ES for the progression of those loads? Switching to 2400, 4227, 4759, 4198 or 5744 might well bring better accuracy at a lower velocity or perhaps even as high as 3200 fps.
SD (Standard Deviation) was noted in the previously posted chart on the right. I shouldn't have used the word "Variance" in the independent axis label, as I should have said variability. Typo.

In my case the tables/plots you’ve posted are hard to read and I can not enlarge them. I understand you like “plots” but a simple list of the actual SD/ES figures with the load in grains would be easy to understand. I have posted similar “plots” in my original RPM threshold thread and found others could not read them well enough to understand having the similar problems with enlarging that I have. Thus i stick with simply posting the actual numbers and making comments. Seems more here understand that way.

RE alternative powders, perhaps, but as far as I've seen to date, folks don't report as high velocities with powders other than lil'gun in the hornet. At maximum loads, they also typically report pressure signs -- which I have yet to encounter even using pistol primers at these maximum velocity loads. Maybe someone has relevant experience in the hornet they could share that would suggest otherwise. I'd be interested to hear loads.

You’re probably aware that I use a M43 Oehler PBL to measure pressures with. I have measured the pressures of numerous .22 Hornet loads using a 21” test barrel with a 12” twist. 12.5 gr of Lil’gun under a 45 gr jacketed bullet produces less psi than factory Remington/Winchester ammunition. It also seems to take at least a 40 gr jacketed bullet to make it burn efficiently. That's why I asked for the actual SD/ES fps data in lieu of a "plot". Loads with H110, 2400 and 4227 will get you into the 2800 – 3000 fps range with 40 gr jacketed bullets at less than CIP MAPs (SAAMI does not list a piezo psi MAP for the .22 Hornet). Using those powders with a lighter weight cast bullet will produce even less psi. Hey, if you don’t want to test with another powder at a lower velocity to find out then that’s ok with me.

Quote:
It is unfortunate also that you are restricted to 100 yards. The non linear dispersion difference between 25, 50 and 100 yards is not near as telling as between 100 and 200 yards.
OK, but Larry -- there is no observed dispersion in the data. I am open to taking further data at 25 and 100 yards, but when do you propose it would be enough? Also, if I kept going out to greater and greater ranges, how would you suggest I distinguish between the effects of air convection/turbulence and this bullet spin rate/range dependent phenomenon of yours? To discount the effects of near ground air speed over the course of the bullet from shot to shot, the effect would have to be fairly dramatic, and the wind obviously pretty calm, right? Well, nothing dramatic was apparent here out to 100 yards.... just saying.

The farther past the RPM threshold the greater the adverse affect of the helical spiral will be. If a load is on the ragged edge of the RPM threshold at ranges of 25 -100 yards it may not be that noticeable. As range increases the helical spiral increases non linearly. Thus there will be a much greater disparity on non linear group size between 100 and 200 yards than there is at ranges shorter than 100 yards.

For example; I ran a test with 311291 in a 10” twist .308W test barrel. I tested group size at 50, 100 and 200 yard. I shot 10 shot groups at each range with a standard load that was below the RPM threshold at 136,400 RPM. I then pushed that bullet above it’s RPM threshold (note I said “its RPM threshold” not THE RPM threshold) at 179,400 RPM. The standard load’s groups at 50, 100 & 200 yards were .7”, 1.3” and 2.5” respectively. We see there the groups expanded in a pretty straight forward linear manner. The 50, 100 and 200 yard groups with the load that exceed that set of components RPM threshold were 2.55”, 4.75” and 14.5” respectively. We see here while the groups were larger at 50 and 100 yards there really isn’t a non linear dispersion. However the very much non linear 14.5” group at 200 yards tells the tale. There was sufficient range for the helical spiral to become very apparent. In the case of your and Bullshop’s tests at 100 yards the “flyers” may very well be those that are over the RPM threshold and the helical spiral is more pronounced, even at 100 yards.
No need to “plot” as the group sizes tell the story sufficiently.

Quote:
Keep in mind that while a 5 shot group is "standard" fare these days it still is not really statistcally valid. A minimal sample of 8 is with 10 being preferred to get a 90% + assurance the data is valid.
Larry, your statement is incorrect (and vague). The statistical adequacy of the population sample size is dependent upon both the nature of the population(s) and the statistical inference that is being made.

Sorry but my statement is not “incorrect” if we are talking ballistics here, not some abstract thought. It is well known among ballisticians that a 5 shot sample is not a sufficient sample. Let me simply quote from the Speer#14 Manual;

“….load seven to ten rounds…….A single five shot group is seldom adequate to give you an accurate picture of the quality of your ammunition. Even though a load produces a five shot group of 0.75 inches, you don’t know if the next group will be 0.55 inches or 1.75 inches. For an industrial level of statistical confidence, four groups of five shots each is considered minimum. ……..A statistical analysis performed by the CCI-Speer Quality Assurance Section, showed that seven shot groups gave the highest degree of statistical confidence with the fewest shots.”

Note also that SAAMI and CIP use a minimum of ten shot groups/test strings.
Now I could be wrong here but I don’t think the entire ballistician industry is wrong.

Quote:
Please do not misunderstand me, I am not being critical here at all. I am trying to help. A bump of the RPM threshold up to 165,000 is not that difficult if we find 3 moa accuracy to be acceptable. As I noted in Bullshop's thread, with such a rifle for varmint shooting 3 moa is not acceptable to me. It is however quite interesting and by no means and easy feat at 3200 fps with no leading.
Thanks Larry -- I do appreciate your feedback, and love your wealth of observations and personal experience. The range report of yours I've read so far was very well written.

I really think a compilation/plot of your data that you used to deduce your rpm theory would be helpful if you ever have the opportunity and inclination to put one together.

If you search for my original RPM thread you will find the charts/plots.

Interesting discussion. Just remember that there is a lot to ballistics that affects the flight of the bullet. Many of these may or may not be apparent at 100 yards or less. And.....the RPM threshold is not a "limit", just a reminder.

Larry Gibson

[DrB]

Larry, frankly, you have just begun to irritate me. By all means share your observations, share your data, even share (but don't push) your pet theories. Please do suggest any means of proving or disproving your theories that would actually be experimentally feasible (and the results of which you would consider if they didn't go your way).

But please, dear lord, stop trying to explain the meaning of the word "threshold" in the english language to me. I have several dictionaries, and apparently, I am more acquainted with how to use one than you are. If threshold meant in the english language what you have abused it to mean, then if I were visiting your home I would be upon the threshold to your living room from the time I was in the middle of your front yard until I walked out your back door. 120,000 rpm? No. 140,000 rpm? No. 165,000 rpm? No. 197,000 rpm? No. For goodness sake, the idea of a threshold is that there is some threshold value at which something changes when you pass it! Give the RPM theory a rest in the context of the present discussion in the face of contradictory physical evidence. If nothing else, park the RPM theory and share a map/spreadsheet based on real physical data. We could all add data points to it and together begin to get a more complete picture.

Also, please do not tell me I am misunderstanding what you said RE acceleration vs. caliber when I have your IM in front of me. Your understanding may have evolved, and you may have new theories, but I can read quite clearly what you typed:

(DrB)"i would expect a larger caliber to have a lower rpm limit."

(Larry)Actually I'm finding just the opposite. Reason being on smaller calibers given the size or amount of defect it represents a larger percentage of the bullets weight/mass. Also the farther from the center of spin a defect is the less effect as the rotational velocity is less, hence less centrifugal force.

While you have just represented that you told me you agreed with my assertion, the fact is that after this IM from you I responded by IM with the equation for rotational velocity as a function of radius, and centripetal acceleration as a function of that, and you did not acknowledge it -- you just quietly went away, and I have not received an IM from you since. No biggie -- just please don't always ascribe my disagreement with you to my "misunderstanding." If I say that, it's often because I am being polite. When you say it, particularly when you misrepresent the content of a discussion, it is easy to interpret as you being disingenuous and condescending.

As far as the state of the evidence goes: Dan posted on remarkably high 3600+ fps velocities with cast bullets, no fouling, and so-so accuracy and your reaction was "slow-down, slow-down it's RPM." I was able to replicate Dan's lack of fouling and essentially the same accuracy with the same bullets and lube at lower RPM and velocity, and your reaction was "slow-down, slow-down it's RPM." Dan was able to get one hole accuracy at WAY HIGHER RPM in the same caliber with a different bullet, and you take no notice of this remarkable (but inconvenient to your theory) result. So far the results here span 145,000 to 196,000 rpm, and 2400 to 3600+ fps with a negative correlation between RPM and MOA, and you still say it's the RPM. Well, if our so-so accuracy is the result of your RPM theory (in spite of the mold-half offset I measured, or the mismatch in gascheck/bullet shank diameters, or the negative correlation in the data (MOA is decreasing with increasing RPM)), and as you say, you can observe this nonlinear group expansion effect easily only after 100 yards, then why in heck are you so stuck on our constant MOA accuracy at less than 100 yards being principally attributable to your pet theory?!! :veryconfu How is there anything in the data we have posted that is primarily consistent with your theory as distinct from the umpteen different suspect inaccuracy causes that occur for loads in general or boolits in particular?

Another thing, please do not presume to know my resume regarding ballistics. I'd hazard to guess there's only one of us here (between the two of us -- I make no assumptions about the membership at large!) who's written Runge-Kutta ballistics integrators, performed CFD on a bullet design, written a navier-stokes flow solver, performed thermochemical equilibrium calculations, knows what an "ensemble statistic" is as it relates to calculating high temperature properties of a gas, has solved for the principle rotational axes and moments of inertia of a body, performed statistical experimental design, performed multivariate regression, etc., etc., etc. If I politely say I do not understand your theory, you might want to consider I'm saying it because your theory as explained doesn't make physical sense. I will be polite and say this even if I think your theory makes no physical sense because I am humble, conversational language is imprecise and so the theory may be difficult to exactly convey, and even if the theory isn't all right there may be a good idea or two within (and because I would prefer to be polite).

I am not, by a long long long shot, the smartest guy Larry. There is an unbelievably huge universe of things I know nothing about, and a small one I have some passing familiarity with. I am always eager for new data and observations as experiments are costly and all of our observations together can facilitate a far better understanding than our limited efforts alone. I strongly believe in profiting from the experience of others, and I strongly believe in the scientific method.

Now, if you would like to continue to politely expand upon your theory in a gentlemanly way, I'd love to talk to you further about it. Depending upon what you mean by "a helical path" I think we can actually physically prove or disprove that part of your theory with one of your load/gun combinations that you are confident exhibit this behavior, using an inexpensive and simple experiment (on your time and dime). Please describe your theory, exactly, as to what is moving in a helical path, roughly what the diameter of this path corresponds to, and what the forward progress per revolution around the path is. We can experimentally take the lateral deviation due to wind and vertical stringing due to muzzle velocity variation right out of the equation. I'd also love to discuss the internal pressure data you have with lil'gun and what primers you may have data with in the hornet.

Just please be so gentle as to leave anything that sounds like condescension out of our conversation, and discontinue the "appeal to authority" arguments... I tend to overreact (badly) to those. :)

Best regards,
DrB

[Bullshop]

I do hope this works out well! It seems we may be on a precipice of new understanding of the limits of boolits and we can now either fall or climb. I hope we climb!

[DrB]

Bullshop, the two biggest questions running around in my mind are how much we can improve accuracy, and what to attribute this non fouling performance to?

What is different that facilitates a ~1000 fps increase? Is it caliber, lube, bullet geometry, gradual acceleration with a reasonable twist, etc.? What combination of the above? You've already tried a different bullet design in 22, have you data yet in 30 cal? It might be interesting to try the lyman 311316 bret suggested, especially in a slower twist barrel...

Thanks again for posting your results and providing the materials for me try to replicate them. :)

[leftiye]

Whatever else is said here, the velocities of both Bullshop's and DrB's results have waaay beyond doubt put us in to another level of possibilities concerning high velocity with accuracy still being possible. As for RPM theory, these results stand so prominently as having "raised the threshold" as to obviate argument. Along with velocity, rpms have gone sky high, and what has been said before must be evaluated in that light. "Resistance is futile".

[Bullshop]

DrB
Caleb did you notice the notation on the target noting the powder I used in the 22 BR with the 72 grain NOE boolit?
It is the alternate powder I suggested you try in your K- Hornet, Alliant Steel.
I do or did intend to try what would be a similar design in 30 cal but right no I am too busy with our subsistence needs to have the time.
I hope to pick up again later in the fall but that introduces another factor into the equation being temp. Our fall will see temps in the -20's and -30's F. Those temps change the properties of lube but being as it is a part of our life we try to battle it as best we can.

[cbrick]

Second, upon fitting and playing with the checks I observed they were not seating flush on the bullet shank with initial finger seating. I measured the bullet shank and arrived at a dimension of .216-.217, and measured the Hornady check ID at the base and found the dimension was .214. Because of this mismatch in diameter, the checks would not seat flush with finger pressure.

Didn't notice this mentioned again since post #1. If you like, PM me and I'll send you some Hornady checks that should fit your bullets check shank to a "T", perfectly flat & square.


After seating gas checks, I found that typically there was not a variance in the minimum and maximum OAL as far as I could detect, so as near as I can tell the checks ended up square, at least to within a thousandth of an inch. Best regards, DrB

Interesting but did you measure the checks "OAL" from side to side or across the center of the check? Did forcing (pressing) them on cause any lead shaving? Is the bottom of the check flat and completely against the bullet base? Is the side of the check an even distance all the way around from the edge of the lower driving band.

Any way, keep posting your testing and results, curious minds need to know.

Rick

[Larry Gibson]

DrB

No need to get irritated, I was under the impression this was a discussion with the intent of improving accuracy at HV with cast bullets. I don’t believe I talked down to you so kindly do not talk down to me. As you mention, that is not persuaint to a "gentlemanly discussion". That is not polite and is the reason I “went away” in our discussions on PMs (I’m assuming “IM” refers to “PMs” as used on this forum?). You wanted charts, plots, etc. and a hard number of exactly where the RPM threshold is. I have tried to explain to you (“expand on my theory in a gentlemanly way) that there is no hard and fast number as it depends on variables. To correlate and example further; I’m sure you understand the speed of sound(?). The speed of sound is generally listed in fps at sea level, at a certain temperature and at a certain barometric pressure. The speed of sound though, is different in fps at higher altitudes, lower altitudes, different temperatures and at different barometric pressures plus other variables. The speed of sound is also different in fps in water, in steel or other substances. The reason the fps is different is because of the variables, i.e. the substances and the conditions. Thus it is with the RPM threshold; the variables (alloy, lube, bullet design, fit, quality of casting, burning rate of powder, etc.) will dictate what the actual RPM rate will be before the centrifugal force becomes strong enough to cause the helical spiral.

Could you give the thread where you and Dan have posted moa groups ("one hole accuracy") at 3200 – 3600 fps without flyers? I seem to have missed that, unless you are discounting the flyers out of the groups.

“Please describe your theory, exactly, as to what is moving in a helical path, roughly what the diameter of this path corresponds to, and what the forward progress per revolution around the path is.”

I have described the RPM threshold many times. I have already posted the basis of it in this thread but will post it here again;

“The bullet is unbalanced or becomes unbalance due to obturation in the bore during acceleration. The unbalanced bullet is forced to conform while in the barrel and its center of mass is revolving around its geometric center. When the bullet is free of the barrel's constraint, it will move in the direction that its mass center had at the point of release. After exiting the muzzle, the geometric center will begin to revolve about the center of mass and it will depart at an angle to the bore (line of departure). At 54,000 RPM to 250,000 RPM, depending on velocity and twist, the centrifugal force can be tremendous. It will result in an outward or radial acceleration from the intended flight path (line of departure) and will try to get the bullet to rotate in a constantly growing helix.”

Generally this means that with a regular cast bullet common today, cast of an alloy with a BHN of 16 – 22, GC’d properly, with a good lube, sized correctly, driven with a medium burning powder in a case with a medium bore ratio capacity will give its best accuracy up through 120,000 – 140,000 RPM. Where, exactly, in there depends on the combination of variables and conditions. Above that the RPM threshold is when the centrifugal force becomes strong enough that the bullet begins to follow a helical path outwardly from the line of departure or intended path. The “diameter of the path” is dependant on the centrifugal force (the higher the RPM over the threshold the higher the centrifugal force and the larger the diameter of the helical spiral will be) and the range at which measured. It is not a constant diameter but increases as the range increases. This is where the non linear expansion of the groups comes from and why it is more pronounced at longer ranges.

The RPM threshold may be lowered in a given cartridge with a given bullet simply by using a faster burning powder. You may very well get 1 ½ moa accuracy in an ’06 with a 10" twist using a 311291 cast bullet with 4895 powder at 1900 fps. But if you switch to Unique powder will you get 1 ½ moa at 1900 fps? No, you won’t because the acceleration (the time/pressure curve) is much quicker with Unique and the bullet sustains more obturation, setback, sloughing, etc. during this acceleration. This creates a much more unbalanced bullet of which the centrifugal force will act on sooner and to a greater degree to begin that helical spiral. Conversely the RPM threshold can be raised by using a slower burning powder than 4895 and we can get 1 ½ moa upwards of 2000+ fps. That of course has an increased RPM. what we have done there is to lengthen the time/pressure curve to lesson the obturation, setback, sloughing , etc. and thus having a less unbalanced bullet on exit from the barrel. Thus there are many variables and conditions that affect exactly at what RPM the threshold occurs so we can not give an exact RPM that it will occur at.

The point being is that at some level of RPM the helical spiral will begin and that is the threshold for that particular cartridge and components. Most every ballistics book/manual has a description of the helical spiral. I use that ballistic definition. The “forward progress per revolution” is dependant on the degree of unbalance and the amount of centrifugal force as already explained. By “per revolution” if you are referring to the revolution of the bullet (spin) then you misunderstand. The revolution of the helical spiral around the line of departure (intended flight path) is not the same as the revolutions (spin rate) of the bullet to maintain point on stability. The bullets may very well maintain complete rotational stability while following the helical spiral caused by increased centrifugal force. If, perhaps, you’re not still understanding my explanation of "helical spiral" then consider the simple example of a balanced tire vs an unbalanced tire as speed/RPM is increased. What occurs to the balanced vs unbalanced tire is the same as what happens to the cast bullet (actually any unbalanced bullet but it's more pronounced and obvious with cast bullets). Consider as you consider the tire that you are looking at a cross section of the bullet along the line of departure.

The RPM threshold is not my “pet theory”. Your use of that terminology within the context you used it makes it obvious you are indeed in a confrontational irritated mood. I am not going to get "confrontational” with you BTW. I don’t believe there is a need for that in a "gentlemanly" discussion between educated individuals. If you don’t subscribe to the concept then present your case. However, please do not ascribe to me definitions (such as a “limit”) that I have emphatically stated are not so. BTW; I used the word “limit” in our PM because that is what you referred to and wanted a hard number as what the “limit’ was. I also told you in those PMs that there was not a “limit” and there was no hard number of RPM for the threshold because it depended on conditions and variables. That is just as I'm saying now.

I do not claim to know everything there is to know about ballistics. I do not know a single ballistician that claims to. I do not claim to be a ballistician either. The laws of physics and gravity are well known and apply to ballistics, that is what I ascribe to. When something occurs, such as those pesky flyers (the “anything in the data we have posted that is primarily consistent with your theory as distinct from the umpteen different suspect inaccuracy causes that occur for loads in general or boolits in particular”), there can be many interrelated aspects occurring to cause unbalanced bullets. What makes it interesting to me is determine what causes them and try to reduce them so we have as close to a balanced bullet on exit from the muzzle as we can. Muzzle velocity variation can easily be determined with the chronograph and considered or discounted if the SD and ES are appropriate and in proportion to each other.

The fact is though, once the bullet leaves the barrel then the external ballistic aspects take over. It is during external ballistics at some RPM level the centrifugal becomes strong enough to cause the helical spiraling of the bullet around the line of departure (intended flight path). That is a known ballistic fact. Wind drift? I generally do not test cast bullet loads in a crosswind of more than 5 mph. How much does a 5 mph wind drift that cast bullet running 3600 fps at 100 yards? Probably less than 1”, more likely ½” or so, thus if the pesky little flyer is out there 2 – 3” then we can discount the wind. If we are shooting in less than 5 mph wind and are watching the wind conditions, as we should be when shooting/testing loads, then lateral stringing due to wind of 2+ moa is caused by something else. When I shoot a 10 shot group at 200 yards of 2.5” and then a 14.5” group at 200 yards under the same wind conditions (my notes show 1-2 mph out of 5 o’clock) I think we can discount the wind as the cause for the larger group.

I was not “appealing to authority” regard the quotations of what are meaningful statistical samples. I was just stating fact, not my own opinion or theory, my apologies that it irritated you. Everything that is occurring here is within the laws of physics, the laws of gravity and ballistics. We need to figure out what it is and then perhaps we can deal with it. To arbitrarily discount anything within those is not scientific. .If we are indeed going to believe in the scientific method in this then let us both maintain open minds so that we may learn. As with Bullshop, I also hope “we climb” in this matter. Lots of critical pundits here but I’m wondering how many of them have given the time, effort and resources to shooting cast bullets at high velocity that a few of us really have?

“I think we can actually physically prove or disprove that part of your theory with one of your load/gun combinations that you are confident exhibit this behavior, using an inexpensive and simple experiment (on your time and dime).”

What is the “experiment”? I am open to it.

Not a problem at all discussing or even further collaborating on pressure tests with the .22 Hornet with Lil”Gun and various primers. I have some 225438s ready to test. I can also break out my Lyman 225107 and cast some up. We can pressure test in the 21” test barrel with 12” twist and then accuracy test, measure the velocity and the BCs in my very accurate Savage M40 with 14” twist. Be my pleasure to work with you.

Larry Gibson

[Larry Gibson]

.......What is different that facilitates a ~1000 fps increase? Is it caliber, lube, bullet geometry, gradual acceleration with a reasonable twist, etc.? What combination of the above? You've already tried a different bullet design in 22, have you data yet in 30 cal? It might be interesting to try the lyman 311316 bret suggested, especially in a slower twist barrel...

Not sure it's "caliber" but have to admit the smaller caliber bullets are harder to select for any visual defects or to weight with a small enough +/-. Seems some of us have been doing well with .22 cals:-P.

Consider bullet geometry or design; The 225107 is a short stubby bullet with minimal lube groove size. This gives less potential for unwanted obturation, setback, sloughing, etc. during accelleration. The result being a better balanced bullet on muzzle exit with a result higher RPM threshold.

No doubt the lube Bullshp and you are using is a factor, in my mind anyways until proven otherwise.

Gradual accelleration or slowing down the time pressure curve with slower burning powders is also certainly a key factor in reducing bullet unbalancing during acclelleration. Idealy we want to use the slowest burning powder at 100% loading density to achieve the desired results within safe psi parameters for the cartridge/firearm used.

Using as slow a twist as possible that will adequately stabilize (not over or minimal stabilization) the bullet used is also a well known factor for increased accuracy. Many cast bullet bench resters use slow twist .30 cal barrels with lighter weight cast bullets at higher velocities with excellent accuracy.

In .30 call I push the 311466 or the LBT 150 gr to 2600+ fps out of my 27.5" Palma .308W with 14" twist. Accuracy is pretty consistent at 1 1/2 moa through 300 yards (farthest range so far tested) with 10 shot groups. That load is at case capacity with the slower powder used in the .308W. I have gone to 2800+ fps in that rifle with 2 1/2 - 3 moa but had to use a faster powder which I believe is causing the deterioration in accuracy. Non linear group dispersion also catches up quickly with the faster powders. Case capacity seems to be the problem.

One of these days I am going to get a 14" twist 28 - 30 Palma barrel chambered in '06. With that case capacity 2800 - 2900 fps seems feasable with the LBT 150 gr bullet or with Lyman 311466. The longer neck of the '06 will also provide better "fit" with both bullets than they do in the .308W. What's possible with a 14" twist or even a 16" twist 28 - 30" barrel chambered in '06 using the Bret mentioned 311316 or the 311465; 3000 -3200+ fps?

Interesting speculation but one of these days.........

Larry Gibson

[DrB]

DrB
Caleb did you notice the notation on the target noting the powder I used in the 22 BR with the 72 grain NOE boolit?
It is the alternate powder I suggested you try in your K- Hornet, Alliant Steel.
I do or did intend to try what would be a similar design in 30 cal but right no I am too busy with our subsistence needs to have the time.
I hope to pick up again later in the fall but that introduces another factor into the equation being temp. Our fall will see temps in the -20's and -30's F. Those temps change the properties of lube but being as it is a part of our life we try to battle it as best we can.

No, actually I hadn't, thank you.

According to my magazine inventory sheet I just passed 27 powders, I think. :) Guess it's time to play with a new one (alliant steel).

RE subsistence fishing and hunting, I do wish I was doing more of that here. I'm bowfishing tomorrow night before sundown, then will be doing some frog gigging with a hunting partner.

btw, enjoyed your packing materials -- it's always interesting to read the local newspaper.

Best regards,
DrB

[DrB]

Didn't notice this mentioned again since post #1. If you like, PM me and I'll send you some Hornady checks that should fit your bullets check shank to a "T", perfectly flat & square.


Rick, thanks for the offer! When I related the shank and Hornady gas check dimensions to Al of NOE, he said the shank dimension was wrong and that the mould should cast a perfect snap fit with the Hornady's... I expressed the concern that it seemed like maybe the cherry was off in that dimension and he said the mould he sent me would be correct.

So anyway, I've got a brand new NOE 225107 mould sitting on my bench, and I reckon I should probably cast some bullets from it and check the shank before taking you up on your generous offer. Hopefully the bullets form this mould should be just perfect in that regard... and should also provide an interesting test point compared against the remainder of my first batch with the .002-.003 offset mold halves.



Interesting but did you measure the checks "OAL" from side to side or across the center of the check? Did forcing (pressing) them on cause any lead shaving? Is the bottom of the check flat and completely against the bullet base? Is the side of the check an even distance all the way around from the edge of the lower driving band.
Rick

Rick, rereading what I wrote that point was very unclear -- sorry. I measured the OAL of the bullet to get a min/max OAL. This occurred on essentially 180 degree opposite sides as it turned out -- min was pretty much constant on one half of the parting line, and max was pretty much constant on the other half of the parting line, with .002 to .003 difference between them. I did this measurement before and after seating of the check. The notion was that if the difference between the min/max OAL was consistent before and after check seating (+ assuming the check is of uniform thickness), the check was seated flat to the base. If the check was canted at an angle, then that angle would end up resulting in a change in the difference between the min and max OAL. Does that make better sense of what I was trying to do? Anyway, because I seemed to be getting consistent differences in OAL before and after check seating, I decided the checks were most likely ending up pretty flat seated, even though they started out not so much because of the diameter mismatch.

RE lead shaving, the die I was using is newish and I don't believe it is one of the old "shavers"... I saw nothing I took as an indication of shaving, but it did appear to me the small crescent shaped area I mentioned of the bullet was touching the die (and planished/shined up by the contact). I don't know that it affected dimensions significantly, but the new batch from Bullshop plus the home cast ones should give me a couple of additional datapoints... Bullshop ran my order through a .228 die to seat the checks and lube, so they are as cast in size.

Best regards,
DrB

[cbrick]

RE lead shaving, the die I was using is newish and I don't believe it is one of the old "shavers"... Best regards, DrB

Hhmmm . . . No, not the sizing die shaving lead. I was refering to the edge of the check shaving lead from the gas check shank as you pressed on an ill fitting check.

Rick

[DrB]

Great Larry! I'm all for a polite, respectful conversation, and I am delighted to hear you prefer the same! :)

If it's all the same to you, I really did not intend for this thread to be another discussion of your RPM theory, and discussing future experimental tests of it distinct from the test documented by my thread here really is a departure from what this thread was supposed to be about.

If it's okay with you, how about I pick up the discussion of your theory on your original thread, or a pertinent thread of your choosing? Please PM a link and I will post my reply to that thread.

Best regards,
DrB

[DrB]

Hhmmm . . . No, not the sizing die shaving lead. I was refering to the edge of the check shaving lead from the gas check shank as you pressed on an ill fitting check.

Rick

Ah -- then I think the answer is "no" to that as well. The mouth diameter of the check was sufficient to accept the shank to about half the depth of the cup. The shank bottomed out in the check before the check cup rim reached the end of the shank, and the check appeared to be seated before fully crimped, so I don't think there was shaving going on there.

On the other hand, I can't say anything (without prying some checks off and looking) about what the check ID may have done to the bullet base corner when the two were forced together during seating (it was an interference fit) since that all ended up inside the crimped check.

Am I missing something, Rick? What are you wondering?

[DrB]

Larry, RE pressure data, I'm interested in any and all data you or someone else may have regarding alternative primer performance with lil'gun in the hornet case.

I've read a few different folks who appeared to have independently arrived at using pistol primers as providing the most consistent performance/accuracy in a hornet. One rational of the experimental result was something to the effect that the weaker primer didn't overpower the crimp/neck-tension on the bullet and uncork the cartridge before the powder ignited. Another rational is that the weaker primer, having less quantity of composition, has less variability, and not much primer is needed for the small case anyway.

Regardless of what theory folks ascribe to, I started using the standard wolf pistol primers after reading of others experimental results (using other than wolf brand small pistol primers), and have had generally satisfactory results. Accuracy is certainly no worse than the small rifle primers I was using, and maybe better. However, I have never done a comprehensive primer test with my K-hornet and lil'gun.

This concerns me in the present context as it seems to me likely that I am not getting as complete/uniform ignition with the cast bullet and wolf primer as I was getting with the jacketed bullet and wolf primer.

Seems to me there may be a more optimal primer out there to get more uniform/complete initial ignition, that would get me back some of those ~200+ fps I lost going from jacketed to cast, and shave several fps off my SD numbers.

Any suggestions from your own or others prior experiments that would narrow the field of candidates for test would be helpful.

Best regards,
DrB

[Larry Gibson]

DrB

Quite frankly I've not done a study/tests of various primers, small pistol or small rifle, in the .22 Hornet with Lil'Gun using cast or jacketed bullets. Years ago, many years prior to my obtaining the M43 Oehler PBL to test psi, I did a fairly comprehensive test of the SR and SP primers available in my area in the .22 Hornet with jacketed bullets using 2400, 4227 and H110. Those were the powders of choice then, mostly H4227. Using a M11 Oehler chronograph with sky screens it was quite apparent that the proponants of using SP primers were correct. The ES of 10 shot strings was lower and accuracy more consistent when SPs were used.

The SPs have a smaller brisance than SRs and were believed to cause less disruption in the smaller case as you point out. It appeared to be correct from my tests so I have used WSPs and CCI 400s since, in all loads with the .22 Hornet because they gave the lowest ES with the best accuracy. All my tests, the exception being with factory ammunition, have been using WSPs with the various powders mentioned. Obviously a revist with SP vs SRs in the Hornet is in order. I can do that with Lil'Gun as it has become my "go to" powder for use with 40 - 45 gr jacketed bullets in the Hornet for my 3 Hornet rifles. Unfortuneately I do not have any Wolf SP or SR primers. I will check and see if I can get any at the local gunshops/stores.

No further discussion of the RPM threshold here then pro or con. However, please do keep an open mind and do not entirely discount it if those pesky little flyers continue to plague you.

Larry Gibson

[troy_mclure]

i honchoed the gb on this mould. i was planning on using it for 5.7fn and .223.

i sold the 5.7 and passed on the mould.

after seeing how well its performing at speed i kinda regret not getting it.

[Bullshop]

A couple things I would like to mention about primers for the hornet and any other small capacity 22. The one primer I have settled on as the most consistently accurate for the small cases is the Federal #100 sp primer. That has proven consistently true for me over many years.
The other thing I would like to address as it is related to primer ignition is firing pin energy. I have proven beyond any doubt at least to myself that the firing pin strike must be consistent and must have a minimum amount of energy to consistently extract a maximum amount of energy from the primer. A variable firing pin strike will cause a variable release of energy from the primer.
This is demonstrable in some rifles that use an adjustable firing pin spring such as my Cooper mod. 38 22 ccm. When for no apparent reason my 22 ccm starts making larger groups that I know it should be the cause is usually traced the the firing pin spring being out of adjustment, loose. Tightening the spring brings the accuracy back to normal.
Another point about primers and also having to do with firing pin strike energy is primer sensitivity and or cup hardness or thickness.
The thing that tipped me off to the vastly different sensitivity of primers due to cup hardness/thickness and or compound make up is in a Ruger single six I have had converted to center fire but in it the firing pin does not strike on center of the primer but well off center.
To shorten up the total of my findings in this regard I will just say that I have found only one brand of primer that is absolutely 100 % positive to ignite and that is the CCI primer. This holds true with the cci brand whether SP or SR or standard or magnum.
All other brands of SP primers will result in some misfires in this gun. The one exception to that is the Rem # 1 1/2. The Rem # 1 1/2 will ignite reliably but the cup is so thin and so soft it will pierce long before I get to the potential velocity of the cartridge. The Rem 1 1/2 I reserve for very low pressure cartridges like 32 short or similar.
There I hope I have made some sense of what I wanted to say or was floating in the dark recesses of my mind.

[pdawg_shooter]

Someone check my math please. 3000fps from a 1 in 10 twist barrel would be 216,000rpm, would it not? MOA accuracy is possible IF you protect the bullet from deformation from acceleration IN the barrel. If the bullet leaves the barrel concentric it will remain so to the target.

[Nrut]

Someone check my math please. 3000fps from a 1 in 10 twist barrel would be 216,000rpm, would it not? MOA accuracy is possible IF you protect the bullet from deformation from acceleration IN the barrel. If the bullet leaves the barrel concentric it will remain so to the target.

Finally !!..
Been going on a 9 months to a year now since I figured that out and have been waiting for you or one of the other PP guys to ask the question if a grease groove bullet is subject to embalance vulgarity after it leaves the barrel due to high RPM, then why doesn't the same hold true of PP bullets..


Sorry DrB for this interjection of RPM again, but this theory has been grating on me since I first heard about it!

Plus, just maybe we can start looking in the right places for high vel. with grease groove bullets by looking more closely at PP bullets..

[pdawg_shooter]

Paper patching is how I achieved MOA accuracy at 3000fps. A 311284 sized .3015 and patched back up.

[BABore]

Finally !!..
Been going on a 9 months to a year now since I figured that out and have been waiting for you or one of the other PP guys to ask the question if a grease groove bullet is subject to embalance vulgarity after it leaves the barrel due to high RPM, then why doesn't the same hold true of PP bullets..


Sorry DrB for this interjection of RPM again, but this theory has been grading on me since I first heard about it!

Plus, just maybe we can start looking in the right places for high vel. with grease groove bullets by looking more closely at PP bullets..

It's all been said before by many others including pdawg. If you can get a well cast, well fitted boolit into the rifling and out the muzzle without deformation, there is nothing for the high rpm's to act apon. Like Bass has repeatedly said here, "It's all about the launch". It can be sucessfully done and it has been demonstrated here many times. PPing just makes your life easier cause it supports and protects the boolit better.

[DrB]

Finally !!..
Sorry DrB for this interjection of RPM again, but this theory has been grading on me since I first heard about it!

No worries. :)

I had the same thought myself, just didn't want to stir the pot here. :D On the other hand, if you've had the thought, and I have, and it's old hat to BABore, etc., then that means a bunch of folks wandering through have had the same thought (and maybe an answer or two) and not posted about it. I had thought to ask 303Guy or one of our other avid patchers what PP velocity (& twist) out of a gun will be when it starts gettting really tricky.

Now that the question has come up if someone has an idea as to cutting edge PP velocity/twists that would be an interesting thing to hear. I was under the impression that folks had shot into the 3000s?

My personal preference would be if we can just limit the follow up to the facts though, without getting into a melee regarding folks theories.

Best regards,
DrB

[DrB]

A couple things I would like to mention about primers for the hornet and any other small capacity 22. The one primer I have settled on as the most consistently accurate for the small cases is the Federal #100 sp primer. That has proven consistently true for me over many years.

Thanks! :)

[pdawg_shooter]

No worries. :)

I had the same thought myself, just didn't want to stir the pot here. :D On the other hand, if you've had the thought, and I have, and it's old hat to BABore, etc., then that means a bunch of folks wandering through have had the same thought (and maybe an answer or two) and not posted about it. I had thought to ask 303Guy or one of our other avid patchers what PP velocity (& twist) out of a gun will be when it starts gettting really tricky.

Now that the question has come up if someone has an idea as to cutting edge PP velocity/twists that would be an interesting thing to hear. I was under the impression that folks had shot into the 3000s?

My personal preference would be if we can just limit the follow up to the facts though, without getting into a melee regarding folks theories.

Best regards,
DrB

Here is a reprint of a post from awhile back:

Back in November of 08 I decided to develop a sub-MOA, 3000fps load for a 30 caliber rifle. It took awhile, but I believe I have “got er done.”
The Rifle.
In order to get the velocity I wanted with this weight bullet I chose a 300RUM in a Savage model 116. It is stainless with a laminated stock. It came from the factory with pillar bedding, and I added glass behind the recoil lug, and under the front receiver ring and tang. I topped it with a Weaver T15 for this test. This rifle will group ¾ to 7/8 with good, jacketed bullet loads.

The Bullet.
The most consistently accurate 30cal bullet I cast is the Lyman 311284 so this is the one I worked with. The alloy is a mix of WW and Linotype. I added lino. until an air cooled bullet tested 16.0 BHN on my Lee tester. The bullet was then sized .3015 with a push through die. This gave me full length bearing surface. The bullet was then patched with 16# green bar printer paper and allowed to dry overnight. I then clipped the tail, lubed with White Label BAC and run through a .310 push through die. This left the bullet .311 and ready to load. The finish weight, with patch, was 202gr.

The Brass.
I used new Remington brass. I full length sized them and sorted by weight allowing no more than +/- 1%. It was then trimmed to length, outside neck turned to .012 thickness, the primer pocket reamed to a uniform depth, flash holes drilled uniform and deburred. I then loaded with a 180gr. Core Lock and H4831 to fireform. The test load was then loaded in UNSIZED brass. I tried H1000, Retumbo, and finally settled on Reloader25. The starting load was 88.0 and I worked up to 93.0. This gave me 3069 with no signs of excess pressure. Oh yes, the primer was a Federal 215. The bullets were seated about ¼ inch into the case and finished seating when the bolt was closed. This gave me an OAL of 3.670.

The Test.
Testing was done over 2 days. Shots were fired over a bench rest with a windage and elevation adjustable front rest and “bunny ear” rear rest. Twenty 3 shot groups were fired allowing the barrel to cool completely. The smallest group measured .760 and the largest was 1.140. The overall average figured out to .992. Mission accomplished, but just barely. So what good is this load? Not much unless you like poking holes in paper. Next step will be to neck size, seat to correct OAL and see how they shoot. Might make a good hunting load that way.

[Larry Gibson]

Someone check my math please. 3000fps from a 1 in 10 twist barrel would be 216,000rpm, would it not? MOA accuracy is possible IF you protect the bullet from deformation from acceleration IN the barrel. If the bullet leaves the barrel concentric it will remain so to the target.

[smilie=b: [smilie=b: [smilie=b: [smilie=b: How long have I been saying it is the unbalanced cast bullet (either in design , casting or unbalanced during accleration) that is adversely affected by the centrifugal force at the bullets RPM threshold and begins the helical spiral???? That's where a totally bad group or those pesky little flyers come from. Nice to see some are finally beginning to understand. A bullet with no defects exiting the muzzle balanced has all the potential for accuracy. [smilie=b: [smilie=b: [smilie=b:

Larry Gibson

[DrB]

Larry, I think some folks may have issue with some parts of the text of your often ctrl-V'ed theory and your conclusions regarding the actual RPM values, and find nothing novel at all about the idea that you can mechanically damage a bullet by too fast an acceleration (either linear or angular), too fast an RPM resulting in exceeding yield or ultimate strength of the alloy, or bullet damage through any of a host of other bullet damage mechanisms.

Doesn't seem like either the idea that defects are bad or too many rpm's can be bad are particularly novel (or interesting unless they make specific testable predictions). If we are all finding the limitations empirically by bumping up against them, and your theory (or any theory) isn't making useful predictions a priori, how is that different from having no theory at all? The utility of a theory is dictated by it's ability to make testable predictions.

Please propose a thread for further discussion on the RPM theory and I'll continue over there. I still haven't gotten your PM with a link... Again, I would prefer that this thread not be a rehash of a debate it sounds like has been going on for years. It probably would be of more utility to future readers if we kept the content together with where you have already posted most of it so the content isn't fragmented.

Best regards,
DrB

[BABore]

[smilie=b: [smilie=b: [smilie=b: [smilie=b: How long have I been saying it is the unbalanced cast bullet (either in design , casting or unbalanced during accleration) that is adversely affected by the centrifugal force at the bullets RPM threshold and begins the helical spiral???? That's where a totally bad group or those pesky little flyers come from. Nice to see some are finally beginning to understand. A bullet with no defects exiting the muzzle balanced has all the potential for accuracy. [smilie=b: [smilie=b: [smilie=b:

Larry Gibson

Somewhere's about 2-3 months after carrying on about how there was an rpm limit on ordinary boolits for us ordinary folk. Yes, limit! The threshhold thingy came about after several posted groups shot above that limit. Then about 10 good people pointed out to you that fit and launch were the key. Or was it when you sent your 311291 mold to Bass and he pointed out the BR nose was well undersized for a 30 cal bore. Somewhere's about then IIRC. Happy you evolved.:bigsmyl2:

[Bullshop]

Interesting to note that we are able to get very consistent 1.5 to 2 " groups using a 55 grain 22 cal boolit in a sabot and fired from a 30/06 (twist uncertain) at 4100 fps.
I guess the sabot like a PP is protecting the boolit from any base damage or ?
These boolits are fired without lube or gas check but have to be sized to fit the sabot.

[DrB]

Makes sense to me, Dan. With the sabot you've basically got a plastic jacketed bullet. Contact with the bore has got to increase local loading of the lead metal.

Depending on your RPM, though, I'll bet you could spin a soft lead bullet past it's ultimate strength, though.

[Larry Gibson]

DrB

Just this one time I'll do this. I believe this is an open forum and I could continue to post here as others have. If you wanted another thread for this discussion (you tell me to start it twice now) you could/should have started it. However, in the context of "gentlemanly discusions" I have started the thread.

http://castboolits.gunloads.com/showthread.php?t=123987

The 'issue' you seem to have is you insist there be a hard and fast RPM figure where accuracy goes bad. Is there a hard and fast velocity where accuracy is best or gets worse with any firearm? Heck no there isn't. All firearms are different in the exact componants and conditions where accuracy will be best, we all know that. If there were hard and fast predictions a priori all we'd have to do is load that. We wouldn't have to do all this "working up loads" and testing nonsense. The point is I can not tell you a cast bullet will be most accurate in your rifle at 1972 fps, 2337 fps or 2489 fps and no one else can. Besides thaat. If that cast bullet was only accurate at 2337 fps then how do make each and every bullet go exactly 2337 fps? You don't. There is and extreme spread of velocity and most often only the average velocity is mentioned. Thus do you really expect me to tell you that accuracy with a cast bullet will go south at exactly 141.389 RPM? Apparently you do want such an unrealistic number.

Well there isn't one, that's why I'm telling you that with regular GC'd cast bullets using an alloy of 15-18 BHN, a good adequate lube, sized correctly for the throat, loaded in a medium sized case for caliber and using a medium burning powder for the case capacity the RPM threshold will be in the 120,000 - 140,000 range. In an '06 or .308W with a 10" twist using a 311291 or similar bullet that correlates to best accuracy will be in the 1650 to 1950 fps range. That is exactly the fps range where most all who use cast in those 2 cartridges with 10" twists find the best accuracy.

If you doubt that then get an '06 or .308W with a 10" test, a 311291 or similar bullet and test it yourself. Now if you want to push the RPM threshold higher then a slower burning powder can do it to a degree. A better designed bullet for the task will certainly help also. It can be done but more attention to detail is necessary to keep the bullet as balanced as possible during casting, loading and accellleration if the RPM threshold is going to be pushed very much higher. At some velocity/ RPM the bullet will become unbalanced because of accelleration at least and it will hit the RPM threshold and accuracy will go south. What that exact RPM is depends on the componants, the skill at which we load them and the ability of the alloy/bullet design to resist obturation, setback, sloughing, etc. during accelleration.

I don't expect a discusion from you here as you've really not responded to any of the points I've made thus far excect to mention "issues" and avoid the examples or points I've made. Perhaps you'll respond on the other thread as you requested.

Larry Gibson

[Larry Gibson]

Somewhere's about 2-3 months after carrying on about how there was an rpm limit on ordinary boolits for us ordinary folk. Yes, limit! The threshhold thingy came about after several posted groups shot above that limit. Then about 10 good people pointed out to you that fit and launch were the key. Or was it when you sent your 311291 mold to Bass and he pointed out the BR nose was well undersized for a 30 cal bore. Somewhere's about then IIRC. Happy you evolved.:bigsmyl2:

BaBore

I have posts going back to March of 2004 regarding my discussions with Bass Ackwards. In all of those I refer the RPM threshold as a threshold and not a "limit". In numerous of those post/PMsI have corrected others, including you, that the RPM threshold is not a "limit". If you have something where I've said it was a "limit" earlier than that please post on the new thread;

http://castboolits.gunloads.com/showthread.php?t=123987

Larry Gibson

BTW; Bass got sub 2 moa accuracy upwards of 2200+ fps with that "ill fitting" 311291 in one '06 rifle and I did the same in 3 rifles. Those loads pushed the RPM threshold upwards of 159,000 RPM. Above that the increasing RPM caught up with that "ill fitting" 311291 despite the best efforts of Bass and I. In other words accuracy went south.

[303Guy]

An observation I made regarding the use of Lil'Gun in the hornet (standard) is that it works better with a heavier bullet in the absence of case neck grip - I didn't size the necks at all. I was using a compressed charge in R-P cases. (I made a tool for my press to compress the powder down to its depth so that it did not push the otherwise loosely seated bullets out. Accuracy was very good and trajectory was consistant. I'm deducing that velocity spread was fairly small.

[leftiye]

Resistance is futile

[DrB]

An observation I made regarding the use of Lil'Gun in the hornet (standard) is that it works better with a heavier bullet in the absence of case neck grip - I didn't size the necks at all. I was using a compressed charge in R-P cases. (I made a tool for my press to compress the powder down to its depth so that it did not push the otherwise loosely seated bullets out. Accuracy was very good and trajectory was consistant. I'm deducing that velocity spread was fairly small.

You said something about this on Dan's original thread, didn't you?

Because of it I tried one load variant (didn't do exactly what you said) that was 17 grains of settled Lil'Gun powder in an unsized fireformed case. There was sufficient lube on the bullet to stick it to the neck ID at the depth I seated it, and then I used a 1/2 turn on a lee collet factory crimp die to stick the case neck to the bullet.

Now, the powder was vibrated down instead of compressed (I can't fit that much powder in the case initially with dropping it). How much powder were you putting in and compressing, and how much compression? Maybe I should post the variants and individual load spreads/SDs... have to see if I can get the charts to show up bigger next time.

Best regards,
DrB

[Bret4207]

A couple things I would like to mention about primers for the hornet and any other small capacity 22. The one primer I have settled on as the most consistently accurate for the small cases is the Federal #100 sp primer. That has proven consistently true for me over many years.
The other thing I would like to address as it is related to primer ignition is firing pin energy. I have proven beyond any doubt at least to myself that the firing pin strike must be consistent and must have a minimum amount of energy to consistently extract a maximum amount of energy from the primer. A variable firing pin strike will cause a variable release of energy from the primer.
This is demonstrable in some rifles that use an adjustable firing pin spring such as my Cooper mod. 38 22 ccm. When for no apparent reason my 22 ccm starts making larger groups that I know it should be the cause is usually traced the the firing pin spring being out of adjustment, loose. Tightening the spring brings the accuracy back to normal.
Another point about primers and also having to do with firing pin strike energy is primer sensitivity and or cup hardness or thickness.
The thing that tipped me off to the vastly different sensitivity of primers due to cup hardness/thickness and or compound make up is in a Ruger single six I have had converted to center fire but in it the firing pin does not strike on center of the primer but well off center.
To shorten up the total of my findings in this regard I will just say that I have found only one brand of primer that is absolutely 100 % positive to ignite and that is the CCI primer. This holds true with the cci brand whether SP or SR or standard or magnum.
All other brands of SP primers will result in some misfires in this gun. The one exception to that is the Rem # 1 1/2. The Rem # 1 1/2 will ignite reliably but the cup is so thin and so soft it will pierce long before I get to the potential velocity of the cartridge. The Rem 1 1/2 I reserve for very low pressure cartridges like 32 short or similar.
There I hope I have made some sense of what I wanted to say or was floating in the dark recesses of my mind.

Dan, remember the Remington Etonix (IIRC) rifles and cartridges introduced a few year back, the ones with electronic ignition? The completely dismal failures as far as sales went? I recall reading an article that spoke of just what you're saying and the claim was that variations would be nil with that system.

Just food for thought.

[Bullshop]

Bret4207
Yes I remember those. I wanted one but felt they were too expensive at about three time the cost of the regular rifle.
Most folks will totally disregard the firing pin condition as it relates to accuracy. I have disassembled some bolts to find a badly gummed up spring from old dry lube and other debris.
For myself having to deal with shooting in extreme cold temp I always strip the system of any liquid or grease lube then re-lube with dry molly.
I once did a test with a firing pin dragging from a liquid lube due to cold temp. @ -50F and got a 500 fps ES from what was proven to be a good load. In another situation where I went hunting with a new to me rifle without first being winterized the rifle failed to fire at all. When I pressed the trigger I could see the striker ever so slowly move forward until the firing pin gently rested on the primer. With that I asked my son for the rifle he was carrying which was my old 35 Whelen which had been winterized and proceeded to harvest our caribou without problem.
The idea of pointing out the possibility of a variable strike firing pin adding to ES and group size may in this case be compounded but the Ruger system of the two piece bolt being used by DrB. He did mention he was using a Ruger 77 K Hornet.
There has been plenty of discussion elsewhere about issues with the Ruger two piece bolt and ways that some folks have come to alleviate the problem.
The one thing regarding the alleged issues with inaccuracy caused by the Ruger two piece bolt system that I am unable to comprehend is why is the Savage Model 40 using a similar two piece bolt system so inherently on average more accurate than the Ruger.
I am now speaking from experiance with the 4 Ruger rifles I have owned in 22 hornet, and strictly with the use of boolits not bullets. Granted I have only the use of one Savage mod 40 to compare to the 4 Rugers but in my experiance with these the Savage is the most accurate of the 5 guns.
Sorry for the divergence in subject matter but it is related to accuracy variables involved.

[Bret4207]

Bret4207
Yes I remember those. I wanted one but felt they were too expensive at about three time the cost of the regular rifle.Primers are still available even if loaded ammo isn't. Must be someone bought a few.
Most folks will totally disregard the firing pin condition as it relates to accuracy. I have disassembled some bolts to find a badly gummed up spring from old dry lube and other debris.
For myself having to deal with shooting in extreme cold temp I always strip the system of any liquid or grease lube then re-lube with dry molly.
I once did a test with a firing pin dragging from a liquid lube due to cold temp. @ -50F and got a 500 fps ES from what was proven to be a good load. In another situation where I went hunting with a new to me rifle without first being winterized the rifle failed to fire at all. When I pressed the trigger I could see the striker ever so slowly move forward until the firing pin gently rested on the primer. With that I asked my son for the rifle he was carrying which was my old 35 Whelen which had been winterized and proceeded to harvest our caribou without problem. Yeah, we'uns that that know cold weather know what common oils do in really cold temps. I have to put a horse down once in -20ish weather and the SKS I hadn't done a good enough job on wouldn't fire. Had to warm the bolt with a heat gun.
The idea of pointing out the possibility of a variable strike firing pin adding to ES and group size may in this case be compounded but the Ruger system of the two piece bolt being used by DrB. He did mention he was using a Ruger 77 K Hornet.
There has been plenty of discussion elsewhere about issues with the Ruger two piece bolt and ways that some folks have come to alleviate the problem.
The one thing regarding the alleged issues with inaccuracy caused by the Ruger two piece bolt system that I am unable to comprehend is why is the Savage Model 40 using a similar two piece bolt system so inherently on average more accurate than the Ruger.
I am now speaking from experiance with the 4 Ruger rifles I have owned in 22 hornet, and strictly with the use of boolits not bullets. Granted I have only the use of one Savage mod 40 to compare to the 4 Rugers but in my experiance with these the Savage is the most accurate of the 5 guns.
Sorry for the divergence in subject matter but it is related to accuracy variables involved.

Good barrel vs garbage barrel!

[DGsmith]

DrB etal
Three things have come to mind. Does the difference between the K hornet and the standard case have any effects beyond capacity. I suspect that the 2 piece both has minimal effect as it has been "tightened". I am thinking that a preimium barrel may have additional effects, as will barrel length? Is it practical/possible to PP a 22 cal?
Great discourse guys

[DrB]

DGsmith.... I was wondering about the bolt thing in relation to the firing pin energy comments. I've always been a little vague on what any slop in the two piece bolt did in the hornet, other than theoretically altering vibrations some (but in a properly bedded rifle should this be a significant effect RE barrel pointing at departure from harmonics)?

I really have no idea, but I do wonder if maybe the two piece design has an effect on the firing pin energy? I haven't stripped a bolt and looked at the design so maybe one of you who have stripped a ruger 77 bolt that far would have a better basis for speculation?

I think I'm ready for the next experimental run. I previously had the best luck with the highest charge, and bullets seated such that the lube groove was hidden. It will be some time before I have some Alliant Steel to test with, so I'll be sticking with LilGun for now.

Here are the factors I'm planning on running (this could get costly in terms of time, so I expect I'll narrow this down!):

Work up to 17+ gr LilGun load and Federal #100 small pistol
Bullshop original NOE 107s (.002-.003 mold offset, will double check & 23 BHN) vs. Bullshop new NOE 107s (<.001 mold offset if any, will double check, & > hardness)
Federal #100 small pistol primers vs. wolf small pistol primers
Seating depth to cover lube groove + crimp vs. seating depth to cover first driving band + crimp to ogive
Sample of 10 weight culled for 1/3 heaviest of population range vs. random sample of 10.


I am still planning on using half neck-sized cases.

A full factorial design here would be 16 variants * (10 rnds each) + ~5 variants (5) = 21 variants and 160+25=185 rounds to load.

Of course, I don't think it probably makes sense to run all combinations so that can be narrowed down quite a bit. Anything that you wouldn't suspect to have an interaction can be run independently from the others.

So I think that means just the primers vs. the seating depth need to be run in combination, and that leaves the following experimental design.

Variants:
pc1: federal primer, 15 gr LilGun (x5)
pc2: federal primer, 15.5 gr LilGun (x5)
pc3: federal primer 16.0 gr LilGun (x5)
pc4: federal primer 16.5 gr LilGun (x5)
pc5: federal primer, 17.0 gr LilGun (x5)

1: wolf primer, seating depth 1 (x5)
2: wolf primer, seating depth 2 (x5)
3: federal primer, seating depth 1 (x5)
4: federal primer, seating depth 2 (x5)
5: federal primer, seating depth 1, Bullshop bullet run 1 (hardness 1) (x10)
6: federal primer, seating depth 1, Bullshop bullet run 2 (hardness 2) (x10)
7: federal primer, weight culled bullets (x10)
8: federal primer, random weight bullets (x10)

Total rounds: 85

Suggestions?

Best regards,
DrB

[DrB]

DrB

Just this one time I'll do this. I believe this is an open forum and I could continue to post here as others have. If you wanted another thread for this discussion (you tell me to start it twice now) you could/should have started it. However, in the context of "gentlemanly discusions" I have started the thread.

Wow, you sure have a way of "being polite." Reread my two posts RE sending me a link to an existing thread of your choice. I stated my reasons.

See ya at your new thread.

[Mauser Rat]

If you introduce seating depth as a variable then it seems that you have brought in two other variables perhaps: crimp and case make. They would need to either be controlled in some fashion such as the use of the Lee Factory Crimp Die at a certain setting and using a standard case manufacture or a minimum/standard case wall thickness at the neck?

And it seems that hardness could be used as a control variable to reduce the test matrix?

Regarding the Wolf vs Federal primer? Could this not possibly be eliminated before the larger study simply by doing a pressure study of each brand and comparing them? Since it is not one of the items that has been discussed previously as a primary variable but is included here to assess the correlation of test results from independent test series?

Sorry for the interruption but I have been trying to follow this for some time and am interested in the results.


Kevin

P.S. Regarding the "other" discussion that is not to be discussed here: It would be quite simple to construct a Finite Element computer model of an imbalanced bullet subjected to a gas force and constrained by the bore for a period of time and then have the linear and angular momentum quantified at a subsequent time when the bore constriction is removed: and plot its trajectory under any other conditions such as side wind, temperature etc that you wanted to impose. The advantage of the model is that it could be calibrated to observed data and be tested over and over under all sorts of conditions and imbalances.

[Larry Gibson]

Wow, you sure have a way of "being polite." Reread my two posts RE sending me a link to an existing thread of your choice. I stated my reasons.

See ya at your new thread.

I'm sure you are quite able to read the current threads on this forum, thought it would be obvious to you as an educated gentleman. I do not answer to your beck and call BTW. I suggest if you want something done you ask me for it and not tell me to do it, that would be the gentlemanly way of it.

Larry Gibson

[DrB]

I'm sure you are quite able to read the current threads on this forum, thought it would be obvious to you as an educated gentleman. I do not answer to your beck and call BTW. I suggest if you want something done you ask me for it and not tell me to do it, that would be the gentlemanly way of it.

Larry Gibson

Larry, I'm not following your new threads, and since it was clear I was asking for a link to an old thread of your choice and you have, I am sure, mentioned your theory in a large number of threads over several years, I think my reason for asking for a link will be clear to just about everyone if not to you.

"Please" is customarily taken as a polite request. Of course it isn't necessary for me to point that out. You either get it or you do not, and I'm sure pretty much everyone here does get it. I don't see anything in the tone of my prior posts that suggested that I expected you to answer to my beck and call, rather, that I expected you to show some common courtesy by not hijacking my thread, particularly in return for my offer to help you with an objective test of your theory on another link. Actually, following your link, quite the opposite is apparent in your first post -- you really do think I should be at your beck and call, and that I owe you something.

Don't worry, I'll be along to the new thread in a bit. I don't think folks will blame me if it's not much of a priority for me (other than that I have already said that I will). Given the track record here, how would I perceive any benefit in terms of an enhanced understanding, or anything other than a non-objective and acrimonious discussion no matter how impersonally I stated the facts?

I did say I would, though, and that will be sufficient.

DrB

[Larry Gibson]

DrB

Nice to see what you say here is correct and what I say is "hijacking" the thread and insinuated to be incorrect. That certainly is objective for a gentleman of scientific bent, eh?

We'll see you over there on the RPM discussion thread. BTW; using the "search" feature here would have gotten you lots of other threads, especiall one in particular. However, the new thread is going well........

Larry Gibson

[DGsmith]

DrB
The test matrix does make sense for ferriting out the prime influences. I'm very intrested in the results, and will consider running it independantly with a regular hornet as well as a K hornet. Where can I get the NOE 107 mold?.

[DrB]

DrB
The test matrix does make sense for ferriting out the prime influences. I'm very intrested in the results, and will consider running it independantly with a regular hornet as well as a K hornet. Where can I get the NOE 107 mold?.

Bullshop was kind enough to make a donation of bullets to me for the test, I'll be glad to do the same for you, or let you borrow the mould.

If you wish to buy the NOE225107 for yourself PM SwedeNelson. When I ordered mine he had a few on the shelf still.

Best regards,
DrB

[DrB]

Guys, I'm going to start canning up the test matrix in thread post 55, prior page soon. Any suggestions for variations or other things to change would be greatly appreciated. I'm definitely going to pay more attention to bullet balance and weights here... I'm hopeful that may shave off at least a half inch from group size on it's own. I think greater seating depth/powder compression + crimp may get me a bit more as well. The federal sp #100's may buy something additional to that, at least some folks have had that experience. Anyway, between the these three at least I hope to pare the gun down to something that's more typical of what I am able to get with a tuned jacketed load using 35 Grain Hornady V-Maxs.

Still trying to track down a local source for Alliant Steel, reckon I'll probably end up mail ordering it. I could explore some of the other fast powders, but I'm kind of reluctant to get away from Lil Gun until I've exhausted the options with it as the pressures have been so consistently (surprisingly) low.

Best regards,
DrB

[303Guy]

Wow! This thread is growing faster than I can keep up! I can't read that fast!:mrgreen:

It's a great thread. It does take a little concentration though.[smilie=1:

On the intact patch question, I do have such a patch to examine. I just want to get all the photo's of it for posterity before I cut the patch off. Previous recovered boolits have shown full transfer of the rifling impressions into the boolit without any sign of slip or break through. The impression I get is that no torque slip occurs. I am going to have to set up a different catch medium that stops the boolit slower so as to recover intact boolit rear shanks from a higher velocity.

Here one can see the 'seam' impression right across the land and groove impression.

http://i388.photobucket.com/albums/oo327/303Guy/MVC-137F.jpg

These are patch fragments which appear to be from the area between the lands.

http://i388.photobucket.com/albums/oo327/303Guy/Withfiller211gr30gr2209Grits-PatchF.jpg

Here is a patch from load development - starting load.

http://i388.photobucket.com/albums/oo327/303Guy/MVC-597F.jpg

The next load level. After that the patch disintegrated completely.

http://i388.photobucket.com/albums/oo327/303Guy/MVC-605F.jpg

Here's an interesting one. The driving face of the rifling impression is 'straight' but the training edge has a step in it. This boolit twisted at that point! That point also happens to be at the gap between the case mout and the leade start. It's as though the stresses 'softened' the boolit at that region.

http://i388.photobucket.com/albums/oo327/303Guy/MVC-524F.jpghttp://i388.photobucket.com/albums/oo327/303Guy/MVC-525F.jpg

I've got more to do which will take a little time as work is interfering with leisure![smilie=1: