Cast bullet velocity limits?

[famdoc2892]

Obviously a newbie question, is there an upper limit for muzzle velocity to avoid leading with CBs? I like to load for 30-06, 308 and 30-30 in addition to handgun calibers, but most info found focuses on handgun loading. As a follow-up, do you compensate for the lower velocity by using a heavier bullet to maintain energy, or reduce your load for CBs overall?

[largom]

I load for rifles only, and a lot of 30 cal. My velocity usually falls between 2000 and 2400 FPS. I increase the velocity until accuracy starts to decline then back off a tad. I do the same for jacketed bullets. In most cases the accurate load is not the fastest velocity. I use my guns for hunting and a deer will not know the difference of a boolit going a couple of hundred feet per second slower. Accuracy is my goal, not speed.

Larry

[Larry Gibson]

In those 3 cartridges an upper limit for muzzle velocity to avoid leading with CBs will be a function of alloy, bullet design, lube used, powder used and fit of the bullet to the throat, along with a few other things. With regular cast bullets of lead, tin antimony alloy of any weight the best accuracy, if the barrels have 10" twists, will be in the 1700- 1950 fps range. If 12" twist barrels best accuracy will come in 1700 - 2200 fps range. Leading as such is not a function of accuracy or velocity but simply the improper use of a componant or lack of such use.

Larry Gibson

[45 2.1]

You can shoot lead alloys at the same velocities you get from jacketed without leading. The problem is accuracy.......... or the lack of it. If you try to load conventionally, your not going to get too much accuracy. Unconventional approachs can produce what you want.

[williamwaco]

The maximum velocity achievable depends on many factors. For most it is around 2000 / 2200 fps
We have reports on this site of one user loading the .223 up to 2600 fps with good accuracy.

The best I have done personally is about 2200 fps with the .30-30 using the Lyman 311041.

You can see some leading vs velocity test results using Lee Liquid Alox at this site.

58 different loads with 15 different bullets with velocities from 700 to 1950 fps.

http://www.reloadingtips.com/pages/exp_111201a_lla_test.htm

I do not "compensate" for the lower velocity. I simply accept it and remember that the herd of 60 million American Bison was annihilated in a period of only a few years using cast bullets at much less than 2000 fps.

[1Shirt]

Lots of variables! Alloy, blt dia, blt length, blt weight, lube, primer variance, etc. etc. etc. and so forth. If looking for a max suggest that is is a trial an error deal based on your weapon, and your accuracy tollerance, etc. Suggest you start with mid vol recommended loads and work up to what ever you consider to be acceptable. Presume you have a chrono?
1Shirt!:coffee:

[pdawg_shooter]

Pure lead will work to around 2200/2250. ACWW to around 2600, and a BHN of 16+ over 3000fps, IF you take the time to paper patch them.

[runfiverun]

as was said velocity isn't the issue, it's keeping accuracy.
protect the boolit at all times from casting to the end of the muzzle and you can increase both.
i don't get worked up over weights too much, i look at how the boolit and the throat mesh together.
start at about 1900 fps and work from there.

[303Guy]

My philosophy is heavier to make up for velocity but that can increase launch pressure which damages the boolit right at the get go. Harder bases and a gas check solves that. So would a slower powder or a lighter charge. Lots of variables. I've never had any accuracy with short boolits. Maybe I didn't try hard enough.

[Bret4207]

I think the believable record went to Bullshop with a 22 wildcat of some kind at 34-3500 fps. That takes a lot of work and very cast friendly gun. For the normal guy, once you figure out your fit and what the variations do to it, 24-2500 would be pretty darn good if it would hold groups. I'm pretty happy down in the 2K area, everything kicks less that way.

[1Shirt]

Yep, someplace between 1800-2200 will usually suit me just fine.
1Shirt!:coffee:

[williamwaco]

I find that accuracy goes south long before leading becomes a problem.

[stubshaft]

I usually run mine between 1800 and 2400 but I shoot alot of sillywett targets. I have run 22's up to 2700 with good accuracy just for the challenge.

[MT Gianni]

I think the believable record went to Bullshop with a 22 wildcat of some kind at 34-3500 fps. That takes a lot of work and very cast friendly gun. For the normal guy, once you figure out your fit and what the variations do to it, 24-2500 would be pretty darn good if it would hold groups. I'm pretty happy down in the 2K area, everything kicks less that way.

Bullshop shot over 4000 fps with cast. He then admitted it was with a 22 sabot in a 30-06 but the projectile was cast. It's in the wording sometimes.
For me it is the trajectory that you get. 2000 fps will surely kill game, can you accurately measure range and bullet drop? AS another member says "get closer".

[waksupi]

Don't sweat velocity. It takes at least a 300fps gain in velocity level to make any real difference in trajectory. As was stated, learn how to get close.

[pdawg_shooter]

+1 on the get closer. Learn to hunt not just shoot.

[famdoc2892]

Wow, talk about a response! But it's good to hear all of you saying the same thing from your experience. To respond to a couple of your questions: I have a 30-30 load for jacketed that runs about 2100fps, and 30-06 that runs about 2400 using IMR 4895. May be able to adapt those loads, not finished/haven't run chrono on my developing 308 load. My available alloys currently are WW and Lino/Pb 50/50.

Don't have a mould yet, haven't selected a lube, still learning on those. Definitely in the market for advice! Thanks again!

[Larry Gibson]

If you cast the bullets correctly and laod tyhem correctly then with your rifles if they have 10" twists you can hold very good accuracy in the 1600 - 1950 fps range with useable hunting accuracy to perhaps 2100 fps. If the rifles have a 12' twist then very good accuracy can be in the 1600 - 2200 fps range with useable hunting accuracy a little higher.

Larry Gibson

[Bret4207]

Bullshop shot over 4000 fps with cast. He then admitted it was with a 22 sabot in a 30-06 but the projectile was cast. It's in the wording sometimes.
For me it is the trajectory that you get. 2000 fps will surely kill game, can you accurately measure range and bullet drop? AS another member says "get closer".

Yup, I remember that, but just before he vanished he had that Cooper or whatever shooting 3400ish with no sabot involved.

[leadman]

I've gotten 3,000 fps in a 223 with good accuracy, but accuracy is better around 2,600 fps.
In my old Savage 110DL 30-06 with hard cast bullets of over 200gr weight I can get over 2,600 fps with 1" to 1 1/2" groups at 100 yards. This is not a fun load to shoot so most of my loads are around 1,600 to 1,900 fps.
In my 22 K-Hornet I can shoot the 2,600 fps loads with great accuracy and no leading. A linotype boolit will really tear a jack rabbit to shreds!

For a new caster IMO the caster should start with loads on the low end and make sure all his components are doing what the should and then work up the accuracy.
Then there is the cost factor. A load of 10gr to 14grs of Unique will load alot of low velocity cartridges. The load for my 30-06 with the 200gr boolit consumes as much powder as a full bore jacketed load. Also takes a toll on my body.

[DrB]

Yup, I remember that, but just before he vanished he had that Cooper or whatever shooting 3400ish with no sabot involved.


+1

Bullshop had a couple of targets he posted, one from a rifle I think chambered in fireball and one in a benchrest of some sort? You'd have to go back to the old posts for specifics, but as I recall his best results were with a bench type setup and around an moa at 100 yds (he had results in this velocity ballpark from two different guns).

I was able to replicate with no special effort his high velocities at around 3200 in a k hornet with no lead fouling, using bullshops lotak lube and the noe225107. Accuracy wasn't great, but I suspect it can be tweaked up to what I would expect from jacketed from the ruger 77.

For accuracy, engraving/getting the bullet going down the bore in a balanced manner appears key. Kicking the bullet too hard initially, too soft an alloy, imbalanced bullets, undersized bullets, or a poor throat/bullet match doesn't seem to bode well.

[Larry Gibson]

For accuracy, engraving/getting the bullet going down the bore in a balanced manner appears key. Kicking the bullet too hard initially, too soft an alloy, imbalanced bullets, undersized bullets, or a poor throat/bullet match doesn't seem to bode well.

Now isn't that the truth............:drinks:

Larry Gibson

[jonk]

It's easy to load cast in the 1400-1900 fps range with good accuracy and no leading. In fact it's hard to mess it up if your bullet fit is even remotely appropriate to your chamber and throat and bore diameter.


As you go over 1900 fps, maintaining a good bore and throat fit, bullet seated just off the lands, and using any decent lube will still be fine... but it starts to get trickier. A crummy lube, poor fit, too big of a jump for the bullet, insufficient lube, rough bore, etc... you might start seeing leading.

This is mainly for gas checked projectiles.

Now, with a good hard alloy, gas check, good lube, smooth bore with sharp rifling, and a mold that fits the throat and chamber well, you can get to 2400 without issue- but it's a learning curve to be sure to achieve this.

I will humbly say that most of my loads are in the 1800-2000 fps range and I only have a few guns I can go faster with with no issues. My hat's off to those here who can, but I think you'd be well advised to start slow and move up.

[Larry Gibson]

Most who go faster than 2000 fps with any real consistent accuracy using regular cast bullets do so with barrels of 12 or slower twists. As mentioned by jonk with some bullets, powders and careful loading techniques some can push to 2200 - 2300 fps with useable accuracy in 10" or faster twist barrels.

I happily run 311466s at 2600+ fps with very consistent 1.5 moa 10 shot group accuracy to 200 yards out of a 14" twist .308W without too much other than normal cast bullet loading technique....there is a very good reason for that but I won't go into it here.........seems as though many are learning the reason........

Larry Gibson

[303Guy]

very consistent 1.5 moa 10 shot group That is astounding accuracy. It equates to something like 0.5 MOA three shot groups.

[Larry Gibson]

That is astounding accuracy. It equates to something like 0.5 MOA three shot groups.

Especially at 2600+ fps with a regular cast bullet.

Larry Gibson

[PWS]

Whew! It's not just me! Glad to hear all the responses suggesting a max velocity in the 1800-2200range, WITH top levels of accuracy.

Despite the occasional reports of phenominal performance (such as jacketed performance with cast...) I'm learning that without cast bullets rarely can withstand the forces needed to boot a bullet more than about 2400fps max without accuracy destroying plastic or erosive deformation.

[pdawg_shooter]

Whew! It's not just me! Glad to hear all the responses suggesting a max velocity in the 1800-2200range, WITH top levels of accuracy.

Despite the occasional reports of phenominal performance (such as jacketed performance with cast...) I'm learning that without cast bullets rarely can withstand the forces needed to boot a bullet more than about 2400fps max without accuracy destroying plastic or erosive deformation.

That is why us paper patchers go through the extra effort. Than we CAN get jacketed velocity and accuracy with cast.

[DrB]

Whew! It's not just me! Glad to hear all the responses suggesting a max velocity in the 1800-2200range, WITH top levels of accuracy.

Despite the occasional reports of phenominal performance (such as jacketed performance with cast...) I'm learning that without cast bullets rarely can withstand the forces needed to boot a bullet more than about 2400fps max without accuracy destroying plastic or erosive deformation.

I haven't played with 30 cal yet at what I would consider high velocities, but it does seem that most folks who have achieved velocities much higher than 2400 fps without catastrophe RE leading/accuracy have done so in the smaller calibers. Makes me wonder what any .50 BMG shooters out there may have observed if any have methodically tried to push lighter slugs to higher velocities.

Also, you have to keep in mind that there are members (and ex-members) of this board who don't bother discussing their high velocity results on the forum any more, which I think is unfortunate. My own personal experience, wandering in as someone with a prejudice against the notion of cast at >3000 fps without leading or reasonable accuracy, was that it was a surprisingly easy thing to replicate. After I posted about doing so, I received a fair number of PMs from others about their own successes. I also found it a benefit to populate my ignore list with the only board member who has enjoyed (and enjoys) that distinction to date. :)

Achieving 3200 fps in 22 K-hornet was no particular problem without sign of leading... all load variants I tested were gas checked, unsized (~> .225, IIRC), around 22 BHN. None leaded/fouled the bore to any identifiable degree even after 80 shots. Group sizes were very strongly correlated to velocity SDs and decreasing in size with decreasing velocity SD and increasing velocity. No identifiable trend was present with respect to increasing RPM or velocity vs. worsening group size. Interestingly, group sizes across three different guns, three different cartridges, about ten different loads, and two different shooters appeared to be decreasing with increasing velocity/increasing RPM. The smallest groups were shot with the fastest RPMs and velocities.

http://castboolits.gunloads.com/imagehosting/154544f5982fe21fbd.png
http://castboolits.gunloads.com/imagehosting/154544e3835a6eb0a7.png

No particular effort was made with the bullets RE sorting by weight etc. These were just plain jane water quenched bullets without notable pedigree.... actually, the ones I shot were measurably imbalanced due to a mold half offset that caused one half of the bullet to be longer than the other (and they still grouped in the same ballpark (about an inch or so larger) as swaged jacketed from the ruger 77!). After calculating the impact on accuracy as a function of bullet imbalance, I am a bit surprised that unsorted cast bullets can shoot as competitively as they can against a swaged precision bullet (which you would expect to be more uniform in density and thus better balanced).

This said, I would never suggest that shooting cast bullets is trivial at most velocities! It is a fact that if you pay no attention to sizing, lube, rifling, chamber throat/lead, powder burn rate, alloy, casting quality, etc, ANY of these variables MAY bite you in the buttocks, a number even at low velocities. For example, even at low velocity an imbalanced bullet will "fling" off target and open up group sizes approximately the same as the same bullet will "fling" due to imbalance at higher velocities.

Now take the instance of launching a cast bullet at HIGH velocity -- push any system to its limits, and you will see greater sensitivity. You should expect the rules necessary for success to be more critical and constraining. I would expect that if I had wandered in piecemeal experimenting (without the benefit of someone to say -- "hey, drill here") I might have come to the same conclusions that so many have come to with regards to cast bullets in general (shooting boolits leads your bore, boolits simply can't be as accurate as jacketed, boolits can't be shot at more than black powder velocities, etc., etc.). Instead I had the benefit of BS saying -- "try this, it worked for me," and that was all it took for me. Shooting cast bullets at greater than 3000 fps unpatched may be more constrained (I haven't attempted it in larger calibers, for example), but it has been demonstrated to my satisfaction that it is possible to replicate with comparable to jacketed accuracy in .224 caliber.

Anyone who has an interest should locate the threads where these trials were laid out and try it themselves.


On a different topic, I think it is fascinating that paper patching can confer such advantages at high velocity. I suspect the advantage is improved distribution of the shear loads from rifling to bullet delaying damage that would otherwise tend to occur at much lower torques. The paper patch also looks to be one heck of a good fibrous gas seal, protecting the bullet from hot gas cutting. One of these days I expect I will have to play with PP... my hat is off to those here who have gone to such lengths to post about their experience with PP.

[pdawg_shooter]

quote: On a different topic, I think it is fascinating that paper patching can confer such advantages at high velocity. I suspect the advantage is improved distribution of the shear loads from rifling to bullet delaying damage that would otherwise tend to occur at much lower torques. The paper patch also looks to be one heck of a good fibrous gas seal, protecting the bullet from hot gas cutting. One of these days I expect I will have to play with PP... my hat is off to those here who have gone to such lengths to post about their experience with PP.

IMHO, the biggest advantage to paper patching is the support given to the bullet while accelerating in the barrel. With paper I have reached over 3000fps in a 300RUM and maintained MOA accuracy. BTW, it has a 1:10 twist barrel. A well cast bullet, correctly sized, and supported
against distortion from acceleration doesn't seem to care how fast it is spinning. I use a slow enough powder to give as near as possible to 100% load density, this also helps prevent distortion. Paper patching is not rocket science, just another tool to get the job done. Yes, it takes some time and effort, but when you get jacketed velocity and accuracy it is well worth it.

[Larry Gibson]

DrB

" Now take the instance of launching a cast bullet at HIGH velocity -- push any system to its limits, and you will see greater sensitivity. You should expect the rules necessary for success to be more critical and constraining.

That is indeed the case. We are in agreement. It is unfortunate you do not see that, nor do the others you mention.

For example, even at low velocity an imbalanced bullet will "fling" off target and open up group sizes approximately the same as the same bullet will "fling" due to imbalance at higher velocities.

That is quite interesting because I have data that reflects just the opposite. You asked me for "data" once and I provided it. Could you please provide your data demonstrating the above? As we have discussed the fliers in your groups earlier perhaps you might "equate" them to a "fling" as perhaps that is what they are? I also notice no "data" showing a testing at 100 and 200 yards to see if they are a "fling" which would be self evident in non linear group dispersion between 100 and 200 yards?

I notice on your posted data here that all of your velocities/RPM are above the RPM threshold of 140,000 RPM. I would ask, as I have in the past, if you have shot any loads below 140,000 RPM and was the accuracy as "good" or was it, in fact, better below the RPM threshold?

Might surprise you and your cohorts to know that many of us have shot similar 3000+ fps 5 shot groups of basically 2.9 - 3.4" at 100 yards that your "data" shows with cast bullets in numerous .22 CFs of .22 Hornet, .221, .223 and .22-250 cartridges. Most with 14 or 16" twists and a couple with 12" twists even. Leading was not an issue but since accuracy was always much better, usually 1 - 1.5 moa with 10 shot groups, below the RPM threshold it was/is obvious that something was amiss at high velocity/high RPM. This was even more apparent when the same loads were tested at 200 yards with 10 shot groups and non linear group expansion was very apparent. The little "flings", as you call them do indeed "bite you in the buttocks".

Nothing about the RPM threshold says cast bullets can't be shot at high velocity, they certainly can. What the RPM threshold tells us is that accuracy will deteriorate. Thus if you could demonstrate 1 - 1.5 moa accuracy below the RPM threshold with the case cast bullets and then only get 2.9 - 3.5 moa accuracy above the RPM threshold, even with just 5 shot groups, then you would not only validate the RPM threshold to yourself but understand it as well.

Since you mention you haven't, perhaps you should try high velocity of 2200 - 2600++ fps in a .30 cal cartridge such as the '06 or similar cartridge with a 10" twist barrel. If you really want to shoot high velocity/high RPM try the 6.5 Swede with cast at 2200+ fps. I'm sure 45 2.1 will help you as he has all the rest of us?

Larry Gibson

[beagle]

I keep waiting for Felix to weigh in here as he's the expert on this, IMO. I've done extensive testing on AC WW alloy with the .223. At around 2400 FPS, groups start to open a bit to around 4" at 100 yards. Past that, it's all over the paper. The allow is just not strong enough to take velocities exceeding 2400 FPS. Felix and I were discussing this and he sent me a sample of babbitt which is copper based and will alloy with the WW mix and make the bullet "stronger" due to the slight copper content. I alloyed some WW alloy with it and cast a bunch of 22-55-SPs and a bunch of 225107s.

With the 22-55-SP, I was able hit 2573 FPS with 14 grains of N110 at about 2" at 100 yards with no leading out of a Number 1 .223.

In the Hornet, a M77 Ruger, I was able to get 2702 FPS and 1" groups at 100 yards and no leading. This load was too hot and I started losing cases so I dropped back to around 2200 FPS and used a 225438HP for my back yard varmint shooting.

I loaded some 30-180-SPs in my Number 1 for a test with impact moly coated bullets and we acheived 2600 plus with that test but they wouldn't stay on a 8 X 11 target at 100 yards. Incidently, no bullets were recovered as they were disintegrating on impact as I tried to dig some up and only found fragments and the occasional GC. Petey, my shooting partner was shooting very hard, impact coated moly bullets made in a special Hoch mould (that he called his "smoothie") with no lube groves at around 2800 FPS and was getting 1-2" groups with a hand lapped Shilen barrel and no leading. There's a writeup in one of the old Fouling Shots on this.

So, accuracy at high velocities can be acheived if you're willing to work at it and think outside the envelope stated by our forefathers.

But, is it worth it? I'm happy to sling cast at 2200 FPS and avoid the hassles. Still, it's fun to discuss./beagle

[felix]

I have not joined the discussion, John, because you are doing just fine. ... felix

[303Guy]

I was able to get 2702 FPS and 1" groups at 100 yards and no leading. This load was too hot and I started losing cases ...What powder were you using? I'm getting 2740fps using Lil'Gun under 55gr j-words and case life is indefinite. So much so I had a case with a separation running half way round the case (a range pick up) getting into the batch and this one took about five reloads before I re-discovered it and threw it out. That crack had not progressed and was in fact blocked with gunge. There is no case elongation.

Copper does indeed toughen the alloy. It can be added by dissolving 'tinned' copper into high tin alloy.

[DrB]

In the Hornet, a M77 Ruger, I was able to get 2702 FPS and 1" groups at 100 yards and no leading. This load was too hot and I started losing cases so I dropped back to around 2200 FPS and used a 225438HP for my back yard varmint shooting.
./beagle

Beagle, did you do anything particular with your 77 to get it to shoot? I can't say I've tried all the tricks with mine, but I have had it looked over by my favorite smith, bedded it, etc., and it just doesn't shoot much under 1.7", even with very methodical load development, jacketed or cast.

I would second 303Guy's thought about Lil' Gun... Even with compressed loads, I have had NO sign of pressure with bullets 45 grains in weight and under in the hornet. SDs with maximum capacity loads got down to about 20 fps as you can see in the chart above.... if you believe the trend, though, it still wouldn't have reduced group size under 2.7" or so. Bullet imbalance impact to group size I believe was around an inch... And so I'm really wishing I'd picked up a CZ 527 instead of a Ruger 77 those years ago. :)

[beagle]

2400. Cases were really feeling the affects and I didn't need that much speed so I cut back. I'm way conservative./beagle


What powder were you using? I'm getting 2740fps using Lil'Gun under 55gr j-words and case life is indefinite. So much so I had a case with a separation running half way round the case (a range pick up) getting into the batch and this one took about five reloads before I re-discovered it and threw it out. That crack had not progressed and was in fact blocked with gunge. There is no case elongation.

Copper does indeed toughen the alloy. It can be added by dissolving 'tinned' copper into high tin alloy.

[beagle]

Just added a decent trigger is all. I have one one of the laminated stock SS jobs and it shoots pretty well. I use it as my yard gun on black birds and feral cats. #2 son has one of the plain janes and it don't shoot worth anything.

I won't blow smoke and say I'm getting 1" groups all day but it will generally throw pretty consistent 1 1/2" groups with the right load. It even does better with jacketed loads but I don't shoot them much as I'm a cast shooter.

I've been Super Gluing the checks before seating. I'm coming to the conclusion that part of the fliers on cast .22 bullets are due to checks coming off after exiting the barrel. Works for me in the Hornet but I haven't taken the time in the .223 or .222.

Anyway, I'm pretty happy with it at .22 WMR velocities as it's quiet./beagle


Beagle, did you do anything particular with your 77 to get it to shoot? I can't say I've tried all the tricks with mine, but I have had it looked over by my favorite smith, bedded it, etc., and it just doesn't shoot much under 1.7", even with very methodical load development, jacketed or cast.

I would second 303Guy's thought about Lil' Gun... Even with compressed loads, I have had NO sign of pressure with bullets 45 grains in weight and under in the hornet. SDs with maximum capacity loads got down to about 20 fps as you can see in the chart above.... if you believe the trend, though, it still wouldn't have reduced group size under 2.7" or so. Bullet imbalance impact to group size I believe was around an inch... And so I'm really wishing I'd picked up a CZ 527 instead of a Ruger 77 those years ago. :)

[Larry Gibson]

Yup, most mentioned have 14" or 16" twist with possibly a 12" twist with the .223. Do the math (including for the '06 with a probable 10" twist) and we see all of them are losing accuracy right 140,000 RPM or slightly before with regular alloys and regular cast bullets. I wonder why that is......[smilie=1:

I conducted a high velocity test today that demonstrates how the adverse affect of increased RPM becomes noticeable and very evident. Recently I switched from M118 match cases to fire formed WW Palma cases. With the thinner WW cases there was greater case capacity and I was able to comfortably get 50 gr of AA 4350 under the 311466U bullet cast of 80/20 linotype/Pb, AC’d, sized at .311 with the 1st 2 driving bands at .300, lubed with Javelina and Hornady GCs squarely and firmly seated on the bullets GC shank. These bullets were from a Lyman 4 cavity mould and other than a visual for defects are non-selected or weighed. Fully dressed they weigh in at 155 gr.

Previously, on several occasions, accuracy with the M118 cases and 49 gr AA4350 ran right at 2600 fps and gave very consistent 10 shot group accuracy of 1.5 moa. The RPM for that load is 133,714 with indications it was on the ragged edge of the RPM threshold at that velocity. Thus with the increased capacity of the WW Palma cases I thought perhaps I might be able to push it past it’s RPM threshold. With the 50 gr AA4350 load the 311466U was pushed to 2678 fps, a gain of 78 fps +/-. The RPM of the faster load was 137,725. Here’s what happened with the testing completed today.

1st target is 10 shots at 100 yards. The velocity was 2678 fps with an SD of 13 and an ES of 43 fps. Average peak pressure was 38,700 psi(M43) with a SD of 600 psi and an ES of 1,900 psi(M43). From an internal ballistic standpoint that is a very uniform load. The Oehler M43 Data sheet is included for DrBs benefit as he likes “data”. Terminally (on target) the results showed some of the shots had exceeded the RPM threshold and were “flings”. I have to admit here that in all my shooting career and study I have never before heard “flyers” referred to as “flings”. But if the good, educated DrB wants to call them "flings" it’s ok by me. Anyways, on target, the 3 top shots strung vertically were the 3 highest velocity shots of the test string (I do track such) and as such also had the highest RPM. The 7 shots that had the lowest RPM/velocities went to zero and grouped within the expected 1.5 moa (1.36 moa to be exact).

Those 3 flyers (flings) indicates that when tested at 200 yards with a 10 shot group a probable 3 shots, or about 30%, would give non linear group dispersion and those shots would be out of the group. Linear group dispersion should be about 3” at 200 yards for 60 – 80% of the shots which shouldn't have exceeded the RPM threshold. I then put a target (“A” Decimal) at 200 yards and continued the test with a 20 shot group. The 1st five shots on the target were the 3 at 6 o’clock in the 10 ring, one of the 6 o’clock Xs on the line and the shot cutting the line in the 10 ring at 3:30. That group showed 1 flyer (fling) out of 5 shots with the 4 shots going into normal group dispersion and the flyer (fling) being non linearly out of the group. I move the scope elevation up ½ moa and continued with the remaining 15 shots.

As we can see on the target 10 of the remaining 15 shots went to group with a linear group dispersion of 3.18”, just as it should have. However, 5 of the remaining 15 shots did not go to group, were flyers (flings) and show definate non linear dispersion. We see a wide, non linear dispersion of those 5 flyers (flings) plus the flyer (fling) from the 1st 5 shot group prior to sight adjustment and should also notice how all the flyers (flings) demonstrate an almost perfect radial dispersion well out of the group. Many times such adverse accuracy affects are not noticed when we use an insufficient sample size such as a 5 shot test string. However, with a sufficient sample size such adverse affects become readily apparent.

As I surmised from the 100 yard target exactly 70% of the shots went to group and 30% of the shots showed definite non linear group dispersion. Total group size is 7” adjusted for the ½ moa sight change. Thus we see that those flyers (flings) do indeed tell us something but without adequate testing we may not understand the “what” that they are telling us. I do find 2678 fps quite with such accuracy to be intriguing and may heat treat those bullets to see if that might push the RPM threshold back above the velocity capability of this load. As of now though, the realistic velocity without exceeding the RPM threshold for this bullet/powder combination would seem to be around 2625 fps. That way, on a hot day, the RPM threshold should not be exceeded and accuracy should remain constant at 1.5 moa or less.

BTW; I just cleaned the barrel and not one spec of leading was found.

Larry Gibson

[303Guy]

My interest in my hornet is its ability to reach and touch those rabbits that won't let me get get near enough for the 22. With j's it's flat out to 180yds. That's a long way for rabbits but such shots present themselves and I'm hopeless at ranging shots. And I have the hornet and would like to use it.

I wonder how a 25-303 would do with cast? It's got a 1-in-10 twist.

[MtGun44]

I would expect that the boolit alloy will fail in tension due to centrifugal force at some
point. Add to that the fact of aerodynamic heating at Mach 2 or higher causing serious
heating which will weaken the alloy further. Not at all surprised at the reports of RPM
limits on boolits.

Bill

[swheeler]

Yup, most mentioned have 14" or 16" twist with possibly a 12" twist with the .223. Do the math (including for the '06 with a probable 10" twist) and we see all of them are losing accuracy right 140,000 RPM or slightly before with regular alloys and regular cast bullets. I wonder why that is......[smilie=1:

I conducted a high velocity test today that demonstrates how the adverse affect of increased RPM becomes noticeable and very evident. Recently I switched from M118 match cases to fire formed WW Palma cases. With the thinner WW cases there was greater case capacity and I was able to comfortably get 50 gr of AA 4350 under the 311466U bullet cast of 80/20 linotype/Pb, AC’d, sized at .311 with the 1st 2 driving bands at .300, lubed with Javelina and Hornady GCs squarely and firmly seated on the bullets GC shank. These bullets were from a Lyman 4 cavity mould and other than a visual for defects are non-selected or weighed. Fully dressed they weigh in at 155 gr.

Previously, on several occasions, accuracy with the M118 cases and 59 gr AA4350 ran right at 2600 fps and gave very consistent 10 shot group accuracy of 1.5 moa. The RPM for that load is 133,714 with indications it was on the ragged edge of the RPM threshold at that velocity. Thus with the increased capacity of the WW Palma cases I thought perhaps I might be able to push it past it’s RPM threshold. With the 50 gr AA4350 load the 311466U was pushed to 2678 fps, a gain of 78 fps +/-. The RPM of the faster load was 137,725. Here’s what happened with the testing completed today.

1st target is 10 shots at 100 yards. The velocity was 2678 fps with an SD of 13 and an ES of 43 fps. Average peak pressure was 38,700 psi(M43) with a SD of 600 psi and an ES of 1,900 psi(M43). From an internal ballistic standpoint that is a very uniform load. The Oehler M43 Data sheet is included for DrBs benefit as he likes “data”. Terminally (on target) the results showed some of the shots had exceeded the RPM threshold and were “flings”. I have to admit here that in all my shooting career and study I have never before heard “flyers” referred to as “flings”. But if the good, educated DrB wants to call them "flings" it’s ok by me. Anyways, on target, the 3 top shots strung vertically were the 3 highest velocity shots of the test string (I do track such) and as such also had the highest RPM. The 7 shots that had the lowest RPM/velocities went to zero and grouped within the expected 1.5 moa (1.36 moa to be exact).

Those 3 flyers (flings) indicates that when tested at 200 yards with a 10 shot group a probable 3 shots, or about 30%, would give non linear group dispersion and those shots would be out of the group. Linear group dispersion should be about 3” at 200 yards for 60 – 80% of the shots which shouldn't have exceeded the RPM threshold. I then put a target (“A” Decimal) at 200 yards and continued the test with a 20 shot group. The 1st five shots on the target were the 3 at 6 o’clock in the 10 ring, one of the 6 o’clock Xs on the line and the shot cutting the line in the 10 ring at 3:30. That group showed 1 flyer (fling) out of 5 shots with the 4 shots going into normal group dispersion and the flyer (fling) being non linearly out of the group. I move the scope elevation up ½ moa and continued with the remaining 15 shots.

As we can see on the target 10 of the remaining 15 shots went to group with a linear group dispersion of 3.18”, just as it should have. However, 5 of the remaining 15 shots did not go to group, were flyers (flings) and show definate non linear dispersion. We see a wide, non linear dispersion of those 5 flyers (flings) plus the flyer (fling) from the 1st 5 shot group prior to sight adjustment and should also notice how all the flyers (flings) demonstrate an almost perfect radial dispersion well out of the group. Many times such adverse accuracy affects are not noticed when we use an insufficient sample size such as a 5 shot test string. However, with a sufficient sample size such adverse affects become readily apparent.

As I surmised from the 100 yard target exactly 70% of the shots went to group and 30% of the shots showed definite non linear group dispersion. Total group size is 7” adjusted for the ½ moa sight change. Thus we see that those flyers (flings) do indeed tell us something but without adequate testing we may not understand the “what” that they are telling us. I do find 2678 fps quite with such accuracy to be intriguing and may heat treat those bullets to see if that might push the RPM threshold back above the velocity capability of this load. As of now though, the realistic velocity without exceeding the RPM threshold for this bullet/powder combination would seem to be around 2625 fps. That way, on a hot day, the RPM threshold should not be exceeded and accuracy should remain constant at 1.5 moa or less.

BTW; I just cleaned the barrel and not one spec of leading was found.

Larry Gibson

Larry: thanks for taking the time to post your results, much appreciated by many including myself I'm sure. Just goes to show what 80 fps can do to groups when you are approaching the threshold. I am one of those guys that has always liked targets(or a least pictures of targets and especially 100 and 200 yds) as opposed to 50 yd targets, graphs and charts, that's just me.:)
Looks like a 14" twist 308 is on my todo list, a 155 gr @ 2600 fps and 1.5 MOA sounds fun. I'd guess your alloy is about 18 bn and the 4350 should just be cleaning up , just the facts mam, remember Dragnet?

Larry I think you made a ten grain typo up top. Thanks again Scott

[badgeredd]

I have further testing to do but I am finding that an alloy that is in part a babbitt that contains a fair amount of copper seems to be strengthening my alloy significantly. This strengthening seems to be allowing considerably higher velocities with very good accuracy. It is my opinion that one can quite easily exceed 2400 fps and still have very good accuracy with the right alloy and still maintaining fit, sizing and lube relationship.

Edd

[Larry Gibson]

Larry: thanks for taking the time to post your results, much appreciated by many including myself I'm sure. Just goes to show what 80 fps can do to groups when you are approaching the threshold. I am one of those guys that has always liked targets(or a least pictures of targets and especially 100 and 200 yds) as opposed to 50 yd targets, graphs and charts, that's just me.:)
Looks like a 14" twist 308 is on my todo list, a 155 gr @ 2600 fps and 1.5 MOA sounds fun. I'd guess your alloy is about 18 bn and the 4350 should just be cleaning up , just the facts mam, remember Dragnet?

Larry I think you made a ten grain typo up top. Thanks again Scott

Scott

Thanks, you were right about the 10 gr error....it's corrected.

Larry Gibson

[Larry Gibson]

I have further testing to do but I am finding that an alloy that is in part a babbitt that contains a fair amount of copper seems to be strengthening my alloy significantly. This strengthening seems to be allowing considerably higher velocities with very good accuracy. It is my opinion that one can quite easily exceed 2400 fps and still have very good accuracy with the right alloy and still maintaining fit, sizing and lube relationship.

Edd

No doubt about that. I've considered adding the babbit but I was hoping for a hunting load with an alloy of around 18 BHN that was still somewhat malleable. Scott was right on the money with the BHN on my Lino/Pb at 80/20 BTW. When I go back to the 225107 in the .22 Hornet I will be adding some babbit to the alloy. I see no reason a 2700 - 2800 standard cast bullet Hornet load out of a 14 or 16" twist barrel shouldn't shoot as well as Jacketed at the same velocities.

Larry Gibson

[nanuk]

would adding copper make the boolit less maliable, more brittle?

I remember (303Guy?) someones comments about using MAPP torch to melt a GasCheck into a melt to add copper....

[badgeredd]

would adding copper make the boolit less maliable, more brittle?

I remember (303Guy?) someones comments about using MAPP torch to melt a GasCheck into a melt to add copper....

My experience has shown that with a good balance (tin to antimony) with a copper enhanced babbitt will toughen a boolit. In using a blend of tin, babbitt, pure lead, and lino one can get a rather hard but still malleable alloy that is not brittle. It won't mushroom in the classic jacketed bullet style but it may rivet. Why the babbitt seems to toughen the alloy and tends to take away brittleness is beyond my understanding at this time. It's my opinion that when one is hunting with a 35 caliber boolit and larger, one really doesn't have to be terribly concerned about expansion if one has a decent meplat on his/her boolit. Because I live in an area where I can't hunt legally with a 30 calibre cartridge in my contender or use a rifle on deer, I can't honestly speak to anything in a hunting situation below 35 caliber. I can however say that a 35 calibre boolit in the 22+ bhn area will definitely put down a deer with authority if it drives through or penetrates deeply without breaking up. :grin: The babbitt seems to help in controlling the break-up part of the equation.

As far as accuracy is concerned, driving a 30 calibre above 2350 fps with the right alloy and still get good accuracy is definitely do-able. At a local get together one forum member was pushing a 238 grain cast bullet out of a 1-9 1/2 twist barrel at a measured 2386 fps with 1 1/2" repeatable groups at 100 yards as witnessed by four other forum members. This was from an old battle rifle. As is often said on this forum, a lot of the old "rules" can and are being proven to be inaccurate with some experimentation. :wink:

Edd

[Larry Gibson]

+1 on what badgeredd said.

The addition of copper making a lead/tin/antimony/copper alloy does indeed "toughen" the cast bullet. This means it resists set back, sloughing or unwanted obturation during acceleration can be driven quite a bit faster, depending on the actual alloy, with accuracy than a standard lead/tin/antimony alloy. By using such excellent accuracy is obtainable as mentioned.

I've pondered that such bullets may give expansion similar to the all copper hunting bullets we see if one can drive them fast enough. The impact velocity level should not need to be as high as with the all copper bullet though. Remains to be seen and the use of a 4 part alloy (lead/tin/antimony/copper) is a pretty much an unchartered field with the use of such alloy in a hunting application(?).

I do know that with a soft malleable alloy my .30, .31, 8mm and .35s that are mildly HP to cause very good expansion are every bit as effective on deer as my .375 and .45 cal rifles using hard cast that do not expand. Yes, dead is dead but the expanding smaller caliber cast bullets kill quicker than non expanding ones and as quick as the larger calibers with non expanding bullets. Thus we find, over practical hunting ranges with cast bullets

There are many things we can do to enhance the accuracy of the bullet alone for higher velocity; we can wrap a copper jacket around it, we can wrap a paper jacket around the bullet and we can add copper to the alloy to "toughen" or strengthen the bullet. All of those methods then takes the cast bullet out of the category of the ternary (3 component) alloy of lead, tin and antimony of which alloy is the preponderance of the alloy used for cast bullets. Doing any of the above will raise the RPM threshold there by giving the potential for accuracy at a higher velocity/RPM. The RPM threshold of 120,000 - 140,000 RPM is for the common ternary alloy (lead/tin/antimony) most use with regular cast bullets. Let us not confuse that RPM threshold with the higher RPM threshold of other types of alloyed or PP’d cast bullets, especially those cast of a harder, tougher 4 part alloy.

Larry Gibson

[303Guy]

In using a blend of tin, babbitt, pure lead, and lino one can get a rather hard but still malleable alloy that is not brittle.You don't want to add tin and copper Babbit. Copper Babbit is tin.

It wasn't me that melted copper gas checks. I dissolved the copper by first tinning it with rosin core solder then submerging it into the molten alloy. Copper will only dissolve in tin so it's best I think to make the copper-tin hardener separately. Be careful not to add too much copper to your alloy. While it strengthens/toughens the alloy and makes it malleable it also messes with the cast-ability of the alloy. Higher tin means higher copper but the copper needs to be no more than the eutectic at the freezing temperature. It's about 0.6% ?

The alloy I made had some crazy characteristics. For one I could measure the hardening over an hour. No quenching required although it did seem to gain about half an hour of natural hardening. Boolits fired into sand would turn completely inside out.

http://i388.photobucket.com/albums/oo327/303Guy/MVC-458F.jpghttp://i388.photobucket.com/albums/oo327/303Guy/MVC-452F.jpg

Pretty cool!

[badgeredd]

You don't want to add tin and copper Babbit. Copper Babbit is tin.

It wasn't me that melted copper gas checks. I dissolved the copper by first tinning it with rosin core solder then submerging it into the molten alloy. Copper will only dissolve in tin so it's best I think to make the copper-tin hardener separately. Be careful not to add too much copper to your alloy. While it strengthens/toughens the alloy and makes it malleable it also messes with the cast-ability of the alloy. Higher tin means higher copper but the copper needs to be no more than the eutectic at the freezing temperature. It's about 0.6% ?

The alloy I made had some crazy characteristics. For one I could measure the hardening over an hour. No quenching required although it did seem to gain about half an hour of natural hardening. Boolits fired into sand would turn completely inside out.

http://i388.photobucket.com/albums/oo327/303Guy/MVC-458F.jpghttp://i388.photobucket.com/albums/oo327/303Guy/MVC-452F.jpg

Pretty cool!

If you take a trip over to Rotometals and gander at their babbitt, you'll notice 4 alloys with fairly high copper contents. They would be #'s 1, 2, 3, and 11. If one alloys a bearing babbitt with pure lead and WW, and makes an attempt to balance the tin/antimony content, you'll be very surprised at just how hard you can make a boolit. You'll also find a great cast-ability to the alloy. If one water drops their castings, you'll get an immediate results in hardness that seems to hold for a good long time.

One attribute I have noticed is it is considerably harder to break the boolit. The alloy seems to be more malleable (for want of any better term). I suspect that a finer and more consistent grain structure results in part due to the copper. I am not a metallurgist or a chemist so that is pure guess on my part but the end results I have experienced seem to point in that direction. Perhaps we have a metallurgist or chemist on site that can share some insight into the mechanics of the alloy. I for one would love to know the precise reason the copper seems to improve the alloy.

Edd

[Larry Gibson]

badgeredd

I visited Rotometals and you got my attention:smile:

Using WWs at 95.5/.05/4 how do you "alloys a bearing babbitt with pure lead and WW, and makes an attempt to balance the tin/antimony content" percentage wise of each with which babbit?

Larry Gibson

[tonyjones]

There is an article titled "The Myth of Arsenic" by Wiljen at the lasc.us site. The article may also be found in Castpics. In this article Wiljen explains that arsenic does not serve as a catalyst in a lead alloy but, rather, serves as a grain refiner when heat treating and quenching cast bullets. Using certified alloys from a foundry for his testing he charts the results obtained using copper, selenium, sulphur and arsenic as grain refiners in a Pb/Sb/Sn alloy. The results are very informative and I encourage anyone interested to look up the article and read it.

I would be fascinated to know the implications of using two modifers, in this case arsenic and copper, in a Pb/Sb/Sn alloy.

I have read several posts here where members discussed their results from using COWW, Pb and a bit of babbit that contained copper. The results reported have certainly caught my attention. Has anyone performed detailed tests that would be willing to post their results?

Could this be part of the solution for those seeking accuracy at high velocity with a maleable bullet alloy and without leading?

Best regards,

Tony

[303Guy]

tonyjones, would you mind posting the link to that lasc.us article, please? I looked under the site but didn't see that one (I'm being lazy right now). I think when the word "catalyst" is used, "grain refiner" is what is being referred to.

'Malleable' would be the right term.

[tonyjones]

303Guy,

I've never figured out how to post a link here. However, if one were to scroll down to the bottom of this page and click on Cast Bullet Notes from lasc.us then click on Index to All Articles (upper right hand corner of the page) then scroll down to Additional Authors and Articles you will find it in the middle of the page right below the head.

Brackafrass! It probably would have been easier to learn how to post a link.

TJ

[303Guy]

Brackafrass! It probably would have been easier to learn how to post a link.Not so easy.[smilie=b:
I just learned a few days ago. I still don't know well enough to actually describe it.;-)

Thanks. (By the way, your instructions are more than two steps long - that's not easy for me either!:lol:)

[tonyjones]

303Guy,

The term catalyst has implications, to me at least, that suggest a chemical reaction. In this case, grain refiners or modifers are terms that are metallurgical in nature. The only qualm I have with the article in question is the way the term catalyst is described. This is picking nits and is not intended as a criticism. The article is excellent. It opened my eyes and got me to thinking.

Regards,

Tony

[303Guy]

Thanks - I found it. Wow - I'm getting good![smilie=w: :mrgreen:

I should get that little youngster in my avatar around. He's ten. He should be able to figure out all these things. (Flippin' youngsters!)

[badgeredd]

badgeredd

I visited Rotometals and you got my attention:smile:

Using WWs at 95.5/.05/4 how do you "alloys a bearing babbit with pure lead and WW, and makes an attempt to balance the tin/antimony content" percentage wise of each with which babbit?

Larry Gibson

Larry and others,

I am using Wiljen's Reloaders Reference which has an alloy calculator in it. The salvaged babbit I've been using is very close to the #2 babbit on Rotometals. What I have was analysed as having the same components and percentages. For ease I just ignored the copper when working up various percentage for alloys. I imagine I could get the percentages precise if I wanted to actually do the math, but I haven't up to now.

The alloy I have been using will be tweaked for more experimentation, but I can give you what I've been using to date. I use 5# COWW +4# pure lead +0.25# #2 babbit. The fairly close percentages come out to 94.8% Pb, 2.25% Sn, and 2.25% Sb with a trace of copper. I've used some other proportions to elevate the antimony and tin, trying to keep the tin and antimony balanced. I've used the alloy air cooled and water dropped...dependent on my intended velocity. Give it a try and let me know if it works for you.

Edd

PS To be honest, the idea of balancing the Sb and Sn is something I recall reading some place and it stuck. Where I read it and why it stuck, I have no idea. I suspect I came across it when I first started playing with my boolit alloy composition.

[jandbn]

For those with an interest, here is the link: The Myth of Arsenic (http://www.lasc.us/WiljenArsenic.htm)

[onceabull]

That's a fine piece of work on alternatives to arsenic..But,nless trap shooting is going to outlawed worldwide, why do we need to worry about sources of arsenic.????? Onceabull

[357maximum]

I stepped into casting my own boolits with no knowledge of what I was doing whatsoever. I did not know all the preconcieved notions about cast. I was able to do alot of what some think is impossible. Being ignorant has it's advantages sometimes. I am not a math scholar or a chart lover. I simply TRY IT and change things till it works.

JUST DO IT...understand it later. :mrgreen:


I use the babbit from the same source as BadgerEdd. It is a great "spice" when you need it. I add 5% of it to my 50ww/50pure and after waterdropping it allows me to do some pretty wicked and wild things and still expands enough to reliably kill deer sized critters in 35 caliber guns.


Using the 50/50+5%.....2600 plus with a 225grainer in the 35 whelen was not even a challenge....I did cheat and use a 14 twist barrel though.:popcorn:

The only limit to cast velocity with accuracy is YOU, the strength of brass/steel and the laws of physics and even them can be "bent" a bit. 2200 to 2400 in most standard sporting rifles is NOT difficult if: The boolit is appropriate and it fits, the alloy is correct, and you choose the appropriate burn rate of powder.

I have killed deer with my WD'ed 50/50 and 50/50+5% babbit and so far it has given me partition like performance and no failures with RNFP/WLNFP designs. It just works.


Have fun and good luck,
Michael

[PWS]

Whew! It's not just me! Glad to hear all the responses suggesting a max velocity in the 1800-2200range, WITH top levels of accuracy.

Despite the occasional reports of phenominal performance (such as jacketed performance with cast...) I'm learning that without significant refinement of most/all of the factors, cast bullets rarely can withstand the forces needed to boot a bullet more than about 2400fps max without accuracy destroying plastic or erosive deformation.

Ooops. Big omission typo...

Still, all the responses indicate that the "typical" velocity ceiling with "normal" casting equimpent, materials, and technique while retaining "good" accuracy remains at the 2000fps ballpark.

[Larry Gibson]

Ooops. Big omission typo...

Still, all the responses indicate that the "typical" velocity ceiling with "normal" casting equimpent, materials, and technique while retaining "good" accuracy remains at the 2000fps ballpark.

Reason being is all of the milsurps and many of the typical rifles that are used with cast bullets have 10" or faster barrel twists.................[smilie=b:

Larry Gibson

[geargnasher]

Sulfur is as effective a "grain refiner" as arsenic in Pb alloys.

Paper patching, as DrB and Pdawg mentioned early on in this thread, seems to provide greater strength in the land bearing area, an almost perfect obturation due to the dynamic seal it creates, eliminates base gas cutting and distortion during the transition from case neck to bore, and probably insulates the base somewhat during muzzle exit like a sabot does to prevent tipping. I have pushed WW and quenched low-antimony alloys to 2700 fps in a .30 caliber 10" twist sporter with the same accuracy that the same alloy will deliver at 2K fps max in a well-fitted grease-groove, gas checked boolit.

My theory on any practical velocity limits has to do specifically with the rifling torque on the boolit. Pressure hasn't much to do with it because slowing the twist seems to increase the useable accurate velocity window, although the pressures might be double. Paper jackets increase the useable velocity of a given alloy three times, and WITHOUT a gas check, so base damage doesn't seem to be the culprit. Nose slump doesn't figure in much either, as the same design boolit can be shot at extreme HV with only a paper jacket added whereas it fails at much lower velocity without the jacket. So the key seems to be strengthening the alloy in a way that it can "hold" the rifling under the extreme pressure of the ever-increasing torsional forces of the lands without deforming. I don't understand this completely, as if there was any significant deformation one would think gas-cutting and leading would occur along with observed accuracy degradation as velocity was increased, but not so in a good load. Anyway, if you strengthen the bearing surfaces of the boolit, this alone will increase your useable accuracy/velocity window.

Gear

[badgeredd]

Here's another article on LASC by our own Felix. It gives some info on the use of babbit.

http://www.lasc.us/FelixBabbitbulletAlloy.htm

Edd

[Larry Gibson]

"Pressure hasn't much to do with it because slowing the twist seems to increase the useable accurate velocity window, although the pressures might be double."

I've done a lot of pressure testing with 10, 12 and 14" .308Ws with cast bullets and have found no evidence to indicate any "doubling of pressure" with the same loads. Actually the pressure differences are well within expected variation between different rifles of the same twist. Yes I've measured the pressure of the same load in different rifles with the same twist. Some days the 10" twist gives a higher psi and some days its the 12 or 14" twist that give the higher spi. I also have found that While pressure can have an influence it is not necessarily tied to the "strength psi" as in the Lee chart.

The fact is that many of us have pushed 2600+ fps with very good accuracy with standard ternary alloyed cast bullets with slower twist barrels. I do it in .308W and 357Maximum has posted here doing it in 35 Whelen. Others do the same with 22 centerfires with 14" twists.

We can theorize all we want but the fact remains; cast bullets are more accurate at higher velocity with lower RPM.

Larry Gibson

[runfiverun]

Sulfur is as effective a "grain refiner" as arsenic in Pb.

Anyway, if you strengthen the bearing surfaces of the boolit, this alone will increase your useable accuracy/velocity window.

Gear

yep,i have only written this a couple of dozen times.
this is how the copper/paper jacket works.
look at the j-4 jacket and the paper jacket, i'd bet they are within about .001 of each other.

[geargnasher]

"Pressure hasn't much to do with it because slowing the twist seems to increase the useable accurate velocity window, although the pressures might be double."

I've done a lot of pressure testing with 10, 12 and 14" .308Ws with cast bullets and have found no evidence to indicate any "doubling of pressure" with the same loads. Actually the pressure differences are well within expected variation between different rifles of the same twist. Yes I've measured the pressure of the same load in different rifles with the same twist. Some days the 10" twist gives a higher psi and some days its the 12 or 14" twist that give the higher spi. I also have found that While pressure can have an influence it is not necessarily tied to the "strength psi" as in the Lee chart.

The fact is that many of us have pushed 2600+ fps with very good accuracy with standard ternary alloyed cast bullets with slower twist barrels. I do it in .308W and 357Maximum has posted here doing it in 35 Whelen. Others do the same with 22 centerfires with 14" twists.

We can theorize all we want but the fact remains; cast bullets are more accurate at higher velocity with lower RPM.

Larry Gibson

You don't follow. I was referring to your step-ladder test with the three .30 caliber rifles and the 10,12, and 14 twists.

How much pressure, burning, say, H4350, does it take to make a 165-grain boolit go 1900 fps? About 21,000 PSI right? That's right in your 10-twist peak accuracy window, right?

NOW, how much pressure does it take to make that same 165-grain boolit go 2600 fps in a 14-twist with the same powder and still be in the accuracy window? About 45,000 PSI, right? THAT'S MORE THAN DOUBLE THE PRESSURE. Same boolit, different accurate velocity windows with different twist rates, double the pressure for the same accuracy potential at much the higher velocity window of the 14-twist. I think it's safe to conclude that pressure alone isn't causing the accuracy to go away at 2K fps in the ten-twist. Savvy?

I've postulated in these threads in the past that exceeding a certain peak pressure might have something to do with the loss of accuracy that you attribute to RPM, but I'm thinking less of that the more I load, shoot, and study.

Gear

[Larry Gibson]

Gear

Yup, that makes sense; more powder = more pressure. I was saying there is essentially little difference in pressure with the same load, whether at 1900 fps or 2600 fps from each twist. One other point; All of those twist (10, 12 & 14) will shoot equally well at 1900 fps with the same bullet (311466 for example). The 14" twist will shoot as equally well as the 12" twist at 2200 - 2400 fps but the 10" twist will not. The 14" twist will still shoot equally well at 2600 fps but neither the 10 or the 12" twist s will. That's with the same load with the same bullet with the same pressures at those respective velocities.

The 10" twist will have close to the same RPM at 1900 fps that the 12" twist has at 2300 fps and the 14" twist has at 2600 fps. That's the point; it's the increase in RPM that causes the inaccuracy, not the increase in peak pressure per se. The 10" twist loses accuracy above 21,000 psi (your figures), the 14" twist loses accuracy above 40,000 psi (what I've actually measured with 4350). Both lose accuracy above 138,000 RPM, No accuracy loss correlation to psi but a strong correlation to RPM.......Savvy?

The age old question we see in the Lyman and NRA cast bullet books and asked many times on this forum goes something like; why can I shoot a 311359 at 40,000 psi out of the M1 Carbine accurately but when I load it to 40,000 psi in my '06 accuracy is non-exhistent? The answer is in the M1 Carbine with a 16 - 18" twist the RPM is manageable for accuracy as it is only pushing 75-80,000 RPM. In the '06 that bullet loaded to 40,000 psi is pushing 25-2600+ fps and 180-190,000+ RPM. As we see the accuracy has no correlation to psi but does to the RPM.

Larry Gibson

[felix]

Very good, Larry! Perhaps your best explanation to date on this RPM matter. ... felix

[PWS]

LEE's 30cal 115gr Soupcan has the reputation of being a go-to bullet when seeking high muzzle velocities and good accuracy.

Perhaps there is a mathematically definable correlation between bullet length and top accurate velocities?

[geargnasher]

Gear

Yup, that makes sense; more powder = more pressure. I was saying there is essentially little difference in pressure with the same load, whether at 1900 fps or 2600 fps from each twist. I remember your tests determining that same load+different twist=same pressure and that observation cut through a lot of BS and speculation, good information to have.

....the 14" twist loses accuracy above 40,000 psi (what I've actually measured with 4350). Both lose accuracy above 138,000 RPM, No accuracy loss correlation to psi but a strong correlation to RPM.......Savvy? Si', Yo Se'.

.....As we see the accuracy has no correlation to psi but does to the RPM.

Larry Gibson

The only part I've never been able to understand about the loss of accuracy above a certain velocity in any given rifle with cast boolits is the basic mechanism that causes the loss. You attribute it to embalance due to boolit damage/deformation, where the embalance causes the boolit's path to trace an ever-expanding spiral, perhaps even a 3-D function of distance (z-axis) where the group will print farther out on the x and y axis as a function of distance in a (your words) "non-linear" fashion. Basically 200 yard groups will be more than double 100 yard groups and so on.

I still can't get my head around why such non-linear groups do not begin to demonstrate a donut shape if this were true. If the boolits were tracing a spiral due to high-rpm embalance, wouldn't they print a pretty obvious ring on the target with few, if any, shots in the center? Shouldn't a 500-yard target printed from boolits fired at 180K RPM be a three-foot donut? (but I haven't seen that trend). Or is it random dispersion due to minute differences in embalance that tend to make the HV impacts scatter throughout the pattern?

Gear

[Larry Gibson]

geargnasher

The only part I've never been able to understand about the loss of accuracy above a certain velocity in any given rifle with cast boolits is the basic mechanism that causes the loss. You attribute it to embalance due to boolit damage/deformation, where the embalance causes the boolit's path to trace an ever-expanding spiral, perhaps even a 3-D function of distance (z-axis) where the group will print farther out on the x and y axis as a function of distance in a (your words) "non-linear" fashion. Basically 200 yard groups will be more than double 100 yard groups and so on.

I still can't get my head around why such non-linear groups do not begin to demonstrate a donut shape if this were true.

Look closely at the 200yard target in my post #38. Note all the flyers are demonstrating that. Also note in the narrative that all of the flyers were the highest velocity shots in the test string of 20 shots. Those were the shots that obviously exceeded the RPM threshold as the rest of the shots with lower velocity went to group in linear dispersion and did not exceed the RPm threshold. The fyers do seem to demonstrate a spiral arc of "donut shape".

If the boolits were tracing a spiral due to high-rpm embalance, wouldn't they print a pretty obvious ring on the target with few, if any, shots in the center?

If all of the shots are over the RPM thrshold and the shots are going off into a helical arc they should indeed demonstrate a "donut shape pattern IF there is a large enough sample of shots to demonstrate it. Also there would need to be a large enough target to capture all the bullets. Additionally you have to understand that the shots may not be evenly distributed around the donut as where they would hit at a given range would depend on the where the helical arc started on the axis of flight and rotation for each bullet.

Also you need to remember that I've said the bullets, after crossing the RPM threshold, may go into a slow helical arc OR they may go off on a tangent. Those bullets going off on a tangent would not demonstrate the "donut" shaped group but would have random dispersion in a non linear fashon.

Shouldn't a 500-yard target printed from boolits fired at 180K RPM be a three-foot donut? (but I haven't seen that trend). Or is it random dispersion due to minute differences in embalance that tend to make the HV impacts scatter throughout the pattern?

In either case , helical arc or tangent, the group dispersion would be non linear just as you describe. This could cause a donut effect or random dispersion......just no way to know that I've determined yet. The problem is one of having a large enough target frame to capture the shots at a far enough distance and to shoot enough shots to see if any pattern develops at any specific RPM over the RPM threshold.

Larry Gibson

[runfiverun]

it's clearly not pressure related.
you can walk up from "the load" at 40k psi at 16-1700 fps through the 4895 at 40k and 1900 fps.
but even changing to the next powder step at 40k doesn't make much of a velocity increase,before the accuracy drops off.
now a combination of the powder step after that, and a manipulated alloy, will move you along in the velocity/accuracy game.

i'm sure something internally and externally is the problem.
fixing one makes things look better,fixing two goes further along.
but fighting the internal issues is the bigger problem.
i find it easier to change the twist rate rather than fight it.

[Larry Gibson]

i find it easier to change the twist rate rather than fight it.

My sentiments exactly. I've been "fighting" 10" twist for 40+ years.

The 12" twist is a lot better but you'll fall in love with the 14" twist..........especially in .30 cal.

Larry Gibson

[badgeredd]

The reason I got into this alloy search is quite simple actually. I believe there are several factors affecting accuracy above a certain pressure/RPM level. It is purely an opinion on my part but I've seen some examples of rifle shooting way past the RPM threshold with an alloy that Larry was not including in his original test. SO my conclusion is there are other factors at work here above and beyond the RPMs. I am not disputing Larry's tests or results, but am trying to, shall we say, move the theoretical threshold to a higher level. I want my rifles to shoot as close as possible to their jacketed bullet performance as I can possibly get. For obvious reasons, changing twist rates on a 100 year old rifle I don't see as an option if one wants to shoot an original battle rifle. I have seen a recent example where the RPM theory can not explain the variation in accuracy. In this particular case a rifle was cut to a shorter length barrel and the previously accurate load wasn,t accurate any longer. I'm of the opinion that muzzle pressure was the problem because going to a faster powder brought the accuracy back. Powder was the only change. Please understand I am not trying to argue with anyone's ideas but I am throwing my findings out there for others to try to see if we can get a "non-standard alloy" to break thru the supposed ceiling of velocity with excellent accuracy.

Edd

[geargnasher]

I haven't done enough shooting at extended range above the point that accuracy drops off with a given load to tell for sure. If it doesn't shoot straight at 100 yards I haven't seen the point to shoot them further except once of twice when I was goofing off to burn a box of ammo that was loaded beyond the accuracy window of velocity for the components used. I do remember getting pretty even dispersion and a round "pattern" at least once, but certainly not enough shots downrange to form any conclusions.

I mentioned in another thread on this topic how we all observe a significant increase in accurate velocity by adding a gas check, and another huge jump in accurate velocity by deleting the check and adding a paper jacket to the exact same boolit from the same alloy, so looking at those factors alone should give us clues to what is going on. (Larry, before you respond I already know you're going to say it's a balance thing related to boolit damage during its trip through the gun, and I tend to agree, but just exactly what is being damaged is still unclear).

Gear

[Larry Gibson]

badgerredd

I am certainly in agreement (or at least hoping so) that adding a 4th metal such as copper to the standard ternary alloy of lead/antimony/tin will indeed strengthen the bullet. Given additional strength the cast bullet should then better withstand the stresses of acceleration. That should mean less imbalance and given a quality casting should mean accuracy to a higher velocity/RPM. How much higher we shall find out, eh?

Larry Gibson

[Larry Gibson]

Gear

If we look at the regular cast bullet with a bore riding nose; The nose, if any clearence is there at all may slough or set back onto the lands and into the grooves. If the alloy has hard spots then the nose may also bend to one side as the bullet also colapses into the scraper groove or crimp groove. This collapse may be even or uneven and doesn't have to be much to unbalance the bullet. The bullet may very well collapse unevenly back a bit into the other lube grooves. The more and deeper the lube grooves the more this may happen. Also if the alloy has too high an antimony content it may have brittle spots that may chip off of the drive bands from friction with the lands and sides of the bore. Depending on the fit and neck clearence the and the rate of acceleration the base of the bullet and bottom dring bands may rivit before entering the throat. How evenly they swage out when forced into the throat and bore determines how much imbalance it causes. How badly the base of the bullet gets deformed so it doesn't exit the muzzle square with the bore.........probably some other things bad happening to the regualr cast bullet but you get the idea.

Now, as you mention, when we add the GC we negate some of those and accuracy improves and we can bush the bullet to a higher velocity before accuracy is lost. Add a PP and we can drive the same bullet even to higher velocity with the same good accuracy. Then swage that bullet into a copper jacket of uniform thickness and we can drive that bullet to as fast as the cartridge will allow. In each case we take steps to negate the imbalancing caused during acceleration which keeps the bullet better balanced. The better balanced bullet can be driven to a higher velocity and RPM with accuracy.

I'm hoping the with the assistence of badgeredd we are onto an additional step of adding the copper to the ternary alloy and getting something close to PP level velocity and accuracy with a regular cast bullet.

Larry Gibson

[tonyjones]

A while back I read a post by BABore. I'm paraphrasing here but Bruce indicated that he added a bit of copper bearing babbit to his 50/50-COWW/Pb alloy when he needed a bit more velocity. Since that mix contains Pb, Sb, Sn, Cu and As I'm wondering if the use of 2 grain refiners/modifers, As and Cu, has the desired effect(s) we're looking for. The roughly 1% of unknown content in COWW and other metal sourcd as scrap certainly clouds this issue.

I'm curious to know if anyone has tested a certified alloy of approximately 95.7 Pb, 2 Sb, 2 Sn, .15 As and .15 Cu.

Best regards,

Tony

[runfiverun]

you'll want more copper than that.
i was adding 1% copper to ww's and 3% tin and was pushing a 12 twist to 2450 over my chrono.
the accuracy was extremely acceptable but i was using open sights, the groups were very consistent.
i was doing this as part of a lube project that i had been working on.
i moved onto another project,and never followed through.
maybe i should revisit the tests i done in the 308 when we first discussed this, but add copper to the mix.

[303Guy]

... I was adding 1% copper to ww's and 3% tin ...Any idea what the WW alloy might have been? This is exactly the information I was looking for. No-one had really worked out the copper/tin/antimony content suitable for casting.

Thanks Larry, I'm with felix.

[nanuk]

303Guy
what is the best way to get the copper into the tin?

[nanuk]

i find it easier to change the twist rate rather than fight it.

My sentiments exactly. I've been "fighting" 10" twist for 40+ years.

The 12" twist is a lot better but you'll fall in love with the 14" twist..........especially in .30 cal.

Larry Gibson


Larry, what is the slowest twist rate you would suggest?

[Larry Gibson]

Larry, what is the slowest twist rate you would suggest?

You have to consider 3 things; 1st is the twist rate to give the selected cast bullet proper stabilization. There are 3 basic classes of bullet stabilization; minimal, adequate and over stabilization. You'll want the bullet to be between minimal and adequate stabilization at the prjected velocity you want to attain.

Second consideration is the RPM at the projected velocity should not exceed 140,000 RPM, preferably 135,000 RPM to give a fudge factor.

The third consideration is case capacity. The cartridge should be able to achieve the projected velocity with a slower burning powder (slow medium to the low end of the slow burners with consistent ignition. Example; the '06 will push to 2700+ fps with a slower burning powder at less psi than the .308W because the case capacity of the '06 allows the use of a slower burning powder.

With the use of a ternary alloy of lead/antimony/tin in a properly designed cast bullet for high velocity;

In .30 cal a 14" twist barrel 26"+ long is about optimum for 2600 - 2650 fps with the .308W. Loading density is at max capacity with 4350/RL19/H4831SC and the RPM threshold falls within that velocity range. More velocity can not be had without using a faster burning powder which raises the psi and gives faster accelleration which then actually lowers the RPM threshold with a loss of accuracy at a lower velocity.

It is my contention that the 311466 or the LBT 150 gr bullets cast of the mentioned ternary alloy can be driven to perhaps as high as 3000 fps with very good accuracy using the 30-06 cartridge in a 28 - 30" barrel with a 16" twist. In the near future I will be ordering such a barrel to find out if my contention is correct. A cartridge with the case capacity of the .308 Norma Magnum would probably be better IF it had the longer neck of the '06 case. As is, all standard magnum .30 cals have necks that are too short to give the cast bullet the full support it really needs for such high velocity levels. The idea is to have the bullet seated in the neck properly and have a tight necked chamber for minimal case neck expansion.

I've also thought that a 16" twist 26"+ barrel chambered for the 22-250 with the shoulder bumped back so the 225462 Lovern bullet would fit into the neck would be an excellent .22 CF cast bullet high velocity cartridge. I would have the scraper groove removed from my mould for that bullet design.

Many years ago a friend had 250 Savage that had been rechambered to .257 Roberts. We were able to get excellent accuracy at with the 257464 at 2550 fps (yes I had an Oehler chronograph back in '75) with old 4831. I didn't really understand the why of getting the accuracy we did at that high of a velocity back then but realize now the rifle had a 14" twist and the cartridge case had a neck length that supported that Lovern style bullet without the GC being below the base of the case neck. It also had a tight chamber neck with made for minimal neck expansion. Thus all the ingrediants were there for successful high velocity accuracy with cast bullets.

Larry Gibson

[303Guy]

nanuk
I did it by tinning the piece of copper sheet then submerging it in the melt. I'd say it's best to add it directly to the tin source before adding the tin.

It dissolves slowly into lead with tin in it. My particular alloy went weird on me so I'm thinking I didn't have enough tin in it. My latest alloy had a chunk of Babbit in it which is around 6.5% copper, 6.5% antimony and around 85% tin. I haven't worked out the percentages yet but if the melt and the molds are hot enough it casts beautifully. It does seem to cast close to mold size.

[felix]

Copper and arsenic form complexes that might have to be controlled independently of one another. Just how, I have no idea on what total mixes do what and when, except that copper demands very consistent stirring a well fluxed pot throughout the casting session. Copper cools very dramatically in the mixes I have used and will be in different locals on each boolit if temps are not well controlled. I would suggest a PID hotplate for the mold before a pour, as well as for the pot. I do know for sure that a coppered boolit will compete well with a PP boolit provided each boolit can be made the same. Copper is an amazing ingredient to our junk alloys and should be used with extreme care to make groups stand out. PPing might be easier with less frustration in the long run for this reason. You can boost most velocities by at least 200 fps without trying too hard using copper for smallish diameter boolits. ... felix

[famdoc2892]

Gentlemen, it's no stretch to say you've blown my mind with your discussion in this thread, and I thank you! Just goes to show how forums can be invaluable in passing along knowledge as I "drink from the fire hose!"

[badgeredd]

Copper and arsenic form complexes that might have to be controlled independently of one another. Just how, I have no idea on what total mixes do what and when, except that copper demands very consistent stirring a well fluxed pot throughout the casting session. Copper cools very dramatically in the mixes I have used and will be in different locals on each boolit if temps are not well controlled. I would suggest a PID hotplate for the mold before a pour, as well as for the pot. I do know for sure that a coppered boolit will compete well with a PP boolit provided each boolit can be made the same. Copper is an amazing ingredient to our junk alloys and should be used with extreme care to make groups stand out. PPing might be easier with less frustration in the long run for this reason. You can boost most velocities by at least 200 fps without trying too hard using copper for smallish diameter boolits. ... felix

Felix,

You been around this cast boolit thing a lot longer than I have so take my following comment FWIW.

I have been messing with the babbit as a source of copper and tin in my alloys. I believe you are spot on the amount of copper that can be successfully alloyed into boolit material. What I am finding to date is the 1% may be a bit on the high side. Also I suspect that the amount of tin in the alloy also affects ones results. There seems to be a correlation between tin and copper content in my experience. After working out a couple mixes, I worked up a spread sheet to figure alloys to include specific copper content using know base metals. One I have been using has 0.4% copper. I have worked up another that will have about 0.6% copper. All of the alloys I have worked up (theoretical and practical) I have tried to balance the tin/antimony content to within 0.05%. Now I have to find a way to incorporate the arsenic content also. My problem has been a way to KNOW what the arsenic content is of a base metal like magnum shot. Once I figure that out I should have a fairly precise alloy calculator figured out.

Edd

[badgeredd]

I had a thought last night about the adding of copper to an alloy and wanted to get some thoughts on the feasibility of it.

This idea goes back a couple years when I got some telephone cable chunks. The cable had sat in a barn for several years before I got it. When I stripped the lead sheathing off of the wire, it was coated inside with copper oxide. I melted down the sheathing and it seemed to be quite hard. It occurred to me that perhaps a fellow could add chemical copper oxide to ones melt to add in copper. What do you chemist types think...is it feasible?

Edd

[popper]

Don't try copper sulfate. Telephone cable sheathing has lots of special stuff in it. Has to be corrosion resistant and strong. Google it and battery grid materials to see what they have to do.

[geargnasher]

Don't try copper sulfate.

That was my first thought! I mean, to try it. I would think it would decompose in hot lead and maybe react to form PbSo2-3 and elemental copper, but I don't know much about relative reactivity and if heat alone would be a sufficient catalyst.

I bet it would stink!

Gear

[runfiverun]

i have been giving copper sulphate some serious thought recently.
to get the elemental copper.
the sulpher is an excellent grain refiner.
i don't know chemistry but i know what works in alloy.
so what am i missing?
you can add both to an alloy
so how is the copper sulphate different than just copper and sulpher?

[geargnasher]

What we're missing here is someone with a serious background in inorganic chemistry. Where's Caleb when you need him? I'm thinking the stuff might could be added to fully melted alloy rather than folded into a carefully maintained "mush" like with straight sulfur.

Maybe I'll try "Ask.com", "What happens when you add copper sulfate to molten wheel weights?" Ha! that should be good for a laugh.

Gear

[runfiverun]

glen fryxell might could answer the question too, he has the back ground.

[whisler]

From wikipedia: At 650 °C, copper(II) sulfate decomposes into copper(II) oxide (CuO) and sulfur trioxide (SO3). Note the C!!!

[popper]

Nasty - toxic gasses!!!! Plus sulfuric acid. I checked into it, but if you find a successful method, I'm interested. I think PbS03 is a hard but flaky salt you can of course get electrically.

[badgeredd]

Telephone cable sheathing has lots of special stuff in it. Has to be corrosion resistant and strong. Google it Didn't find a thing on cable sheathing. and battery grid materials not in the same class to my knowledge to see what they have to do.

How about pointing to a place to back up that warning. :confused: This is the first I've heard about toxins (beyond lead) contained is phone cable sheathing which is lead alloyed with antimony and tin for strength and corrosion resistance.

The green deposits I found inside the cable and some of which deposited on the lead alloy sheathing was copper oxide...copper rust for want of a better terminology. I am wondering if our normal wood sawdust or wood stir sticks might possibly be a catalyst to help break the bond between the oxygen and copper atoms. I was hoping that perhaps we have a person among us that has a solid back-round in chemistry and possibly some suggestions.

Edd

[runfiverun]

SO2 is sulpher dioxide or sulpheric acid which can be neutralized with K-31 or soda ash.
sulpher trioxide is different.

if that's truly 650 centigrade i think i can easily stay under that.

y'all know this stuff is used to remove tree roots from sewer lines,
is soluble in water, and can be used to copper plate lead boolits with an electrical charge.

there's other way's to get what i want done, just looking for a simpler repeatable method.

[badgeredd]

there's other way's to get what i want done, just looking for a simpler repeatable method.

RFR, I couldn't have said it better. In my mind, there has to be a rather simple way to add a know amount of copper to our boolit alloy. That is why I started experimenting with the tin based babbit in the first place. AND I have figured out a alloy calculator to give me the amount of copper that is present in my alloys using know babbit mixes...but babbit is rather expensive so my quest goes on for a simpler way to add copper that isn't labor intensive.

Edd

[mauser1959]

I realize that this is an old thread , but I have a question for you guys that shoot a lot more high powered rifles then I . I was recently given a Remington 721 in 270w . All the information that I have found seems to point to the fact that this rifle probably has a 1 in 10 twist . What would be the accuracy point for the gun be ; just an educated guess ? Also what would be the preferred weight of the best bullet ? Would the difference in cast versus ; jacketed bullets make a way the bullet would stabilize . I am wishing to go to a 150 grain bullet , whether gc cast or jacketed . I really need input on what is going on . I hate to admit this , but I normally just shoot pistol bullets that I cast .

[Larry Gibson]

With a 150 gr cast bullet (GC'd) your best accuracy will come in the 1800 - 1950 fps range depending on the powder and bullet design used given good casting and loading techniques.

Larry Gibson

[303Guy]

mauser1959, have you considered paper patching? That would give you jacketed performance and if I'm not mistaken, a 260 mold would make the right sized core. That aside, I'm also interested in how copper affects velocity.

[1Shirt]

I shoot cast for a number of reasons, and economy of course is a primary one. However, the pleasure of shooting a less recoiling rifle shooting moderate velocity cast bullets, ranks a close second. The fastest I have ever tried to push a cast in a rifle was about 2500-2600 in a couple of 22 centerfires. They shot accurately, but I realized that if I wanted those vols from a 224 or 245 bullet, I would want to shoot over 3000 or so, and would go with jacketed. Most of my 30's shoot fine between 1600-1800, and if I want to hunt them, on up to 2200 or so accurately. The driving adage that "speed kills" kind of applies to higher vol cast bullet shooting in rifles. To me it kills the enjoyment of shooting cast.
1Shirt!

[mauser1959]

I am trying to figure this rifle ballistics out , and after reading Larry realized he was on a similar page as I .I will have to send the particular rifle back to Remington for a trigger job , but i think it will make an awesome coyote rifle , especially with Ziese glass on it; Has a redfield peep on it . I am curious where accuracy is lost on a jacketed bullet , as opposed to say a bhn 25 alloy. All of these years I have shot factory rifle rounds and always figured if you slowed down the twist you could up the speed . I hate when I am the least informed in the class .......... thanks all for bearing with me .

[303Guy]

if you slowed down the twist you could up the speed Pretty much, it seems. Unless you want heavier boolits. I'm quite pleased my Brits have a 1 in 10 twist cause I like heavy boolits. In some ways it's not a handicap if one shoots below 1800fps and it's good for subsonic heavies too. But for me high velocity would be quite difficult to attain with any semblance of accuracy. An interesting point is that going over 3000fps requires a little faster twist than below that. Air destabilization forces become quite intense as velocity increases.

[pdawg_shooter]

I have 2 458s, one with a factory 1/14 barrel and one I built with a 1/22 twist douglass barrel. With paper patching there is no difference in accuracy. I have taken a 430gr bullet over 2300 and can see no difference.

[Larry Gibson]

I have 2 458s, one with a factory 1/14 barrel and one I built with a 1/22 twist douglass barrel. With paper patching there is no difference in accuracy. I have taken a 430gr bullet over 2300 and can see no difference.

Both are still well under the RPM threshold. Doubt you'll want to take either above the RPM threshold (even if psi permitted) as recoil would be brutal.

Larry Gibson

[waksupi]

Larry, I am absolutely miserable at math, even with a calculator. Could you start a thread, and post the approximate velocity limits for various barrel twists? I realize I am asking a lot, but I think it would be a good reference for people to check, me included. It would most likely be sticky material. Heck, the thread could even be closed, to prevent any extraneous chat on that particular topic. Dissenters could start their own.
I don't want to get the old "yes you can/no you can't" argument going again. You and I know this isn't etched in stone, but the guidelines would be great to have here.

[303Guy]

Excellent idea, waksupi. I need such a table right now - I'm trying to decide which barrel to buy. Please do, Larry, it would be appreciated by many.

[Larry Gibson]

Ok guys, I can do that. I already have it done but I'm on the road for a couple months and guess where it is? I'll calculate the velocities and post a table. Wemust keep in mind though that the RPM threshold is not a "limit" as such and the RPM/velocity does vary depending on twist, bullet design, alloy and powder burning rate used. The table I'll post will be a spread of velocity for each twist that is 120,000 - 140,000 RPM. That is most often where the RPM threshold will be with regular GC'd cast bullets shot out of rifles.

Please do imediately close the thread I post with the table. If some want to complain they can start a different thread or go visit "we know who" over on AR. However, if anyone has genuine questions I will be glad to answer them on another thread or via PM.

Larry Gibson

[waksupi]

Ok guys, I can do that. I already have it done but I'm on the road for a couple months and guess where it is? I'll calculate the velocities and post a table. Wemust keep in mind though that the RPM threshold is not a "limit" as such and the RPM/velocity does vary depending on twist, bullet design, alloy and powder burning rate used. The table I'll post will be a spread of velocity for each twist that is 120,000 - 140,000 RPM. That is most often where the RPM threshold will be with regular GC'd cast bullets shot out of rifles.

Please do imediately close the thread I post with the table. If some want to complain they can start a different thread or go visit "we know who" over on AR. However, if anyone has genuine questions I will be glad to answer them on another thread or via PM.

Larry Gibson


Larry, when you post it, let me know, and I will close it. You may be able to do it yourself, scroll down on the page, and I think you can do it. If extraneous posts show up there before I can close it, I will just remove them.

[Larry Gibson]

Appreciate that, will do.

Larry Gibson

[303Guy]

Thank you, Larry. :drinks:

[swheeler]

pdawg at 2300 fps you are approx 118k rpm in the 14 twist and only 75K rpm in the 1:22, good reason you can't tell any difference. I think a chart by Larry is a very good idea and will help many find a velocity where top accuracy is a easier to attain.

[303Guy]

Just a question; the spin rate of a large diameter boolit needs to be much lower than a small calibre one. Does anyone know where to find the radial force calculation?

Another question; to what extent does alloy strength and ductility affect maximum velocity and related spin?

[mauser1959]

this is one of the most informative threads that I have ever read here , in all of my years here .

[C.F.Plinker]

Here is an attempt at an RPM threshold chart that may serve until Larry has time to put a better one together. The first column is the twist in inches. The top number in the second (and third and fourth) columns are the RPM thresholds suggested by Larry in Post #110. The rest of the numbers are the velocities that will reach that RPM threshold in a barrel of that twist.

Velocities to reach RPM threshold
RPM threshold
Twist 120000 130000 140000
7 1167 1264 1361 fps
8 1333 1444 1556
9 1500 1625 1750
10 1667 1806 1944
11 1833 1986 2139
12 2000 2167 2333
13 2167 2347 2528
14 2333 2528 2722
15 2500 2708 2917
16 2667 2889 3111
17 2833 3069 3306
18 3000 3250 3500
19 3167 3431 3694
20 3333 3611 3889
21 3500 3792 4083
22 3667 3972 4278
23 3833 4153 4472
24 4000 4333 4667


Please look this over and give comments that can be used on the next version of the table. I apologize for the fromatting as I am not as computer literate as many.

[Larry Gibson]

Just a question; the spin rate of a large diameter boolit needs to be much lower than a small calibre one. Does anyone know where to find the radial force calculation?

Another question; to what extent does alloy strength and ductility affect maximum velocity and related spin?

Rinker's book on Ballistics will give you that information. I imagine researching ballistics on the internet might also.

Larry Gibson

[Larry Gibson]

I've posted the chart on this forum.

Larry Gibson

[303Guy]

Thanks, Larry. So, is that independent of caliber then? Another question, hows does boolit length effect the threshold?

[Larry Gibson]

Thanks, Larry. So, is that independent of caliber then? Another question, hows does boolit length effect the threshold?

Larger caliber bullets fair a bit better becase a given defect is generally a much smaller % of the mass and and if a surface defect, most often what is created during acceleration. The surface defect is also farther from the center of spin. Additionally large calibers have slower twists and many times their max velocity is below the RPM threshold range.

The longer and pointier a cast bullet nose is, especially if unsupported, the lower the RPM threshold will be.

Larry Gibson

[303Guy]

Thanks. I understand the unsupported nose concept, it's the fully supported long round nose boolit I am asking about as those would seem to be subject to a lot of yaw if unbalance at the rear or nose but then the yaw may be dampened by the distance from the base or nose - see why I don't understand? Also, the long boolit may have a smaller stability factor. But, one often hears of a longer boolit being more accurate in a particular gun than a shorter one but that would be due to throat alignment mainly.

[TooTallDean]

TWO YEAR BUMP.


That is a lot of info to digest. And well worth doing so!
Someone from another forum (CanadianGunNuz.com) pointed me to this thread.
I have done some casting in the past for a muzzle loader rifle and a C&B revolver, but I am new to casting for Centre-fire rifles.

I notice this thread does not go into Powder Coated boolits at all, probably due to no new posts in the last two years.
So, has there been any testing to see if PC affects the Max RPM?

I would like to cast for a Lee-Enfield and an M-1 Garand. Both are 1-10".
For the L-E, I can go with a heavy boolit to make up for the low velocity, or use a lighter load like 16gr of #2400
http://castboolits.gunloads.com/showthread.php?13425-Cast-Bullet-Loads-for-Military-Rifles-Article

But the Garand gas system needs to stay within a set range. I dont think that 16gr would cycle a Garand?
Also, it was noted before that a slower powder is easier on a cast lead boolit. However, a slower powder is NOT recommended for the Garand gas system, as it creates too high a port pressure. This can damage parts. H4895 or IMR4895 is best.

So, how to build an accurate, reliable functioning load for the M-1? Hard cast WW, PC'ed and water quenched? Or try PP?

Thanks!

[Jupiter7]

TWO YEAR BUMP.


That is a lot of info to digest. And well worth doing so!
Someone from another forum (CanadianGunNuz.com) pointed me to this thread.
I have done some casting in the past for a muzzle loader rifle and a C&B revolver, but I am new to casting for Centre-fire rifles.

I notice this thread does not go into Powder Coated boolits at all, probably due to no new posts in the last two years.
So, has there been any testing to see if PC affects the Max RPM?

I would like to cast for a Lee-Enfield and an M-1 Garand. Both are 1-10".
For the L-E, I can go with a heavy boolit to make up for the low velocity, or use a lighter load like 16gr of #2400
http://castboolits.gunloads.com/showthread.php?13425-Cast-Bullet-Loads-for-Military-Rifles-Article

But the Garand gas system needs to stay within a set range. I dont think that 16gr would cycle a Garand?
Also, it was noted before that a slower powder is easier on a cast lead boolit. However, a slower powder is NOT recommended for the Garand gas system, as it creates too high a port pressure. This can damage parts. H4895 or IMR4895 is best.

So, how to build an accurate, reliable functioning load for the M-1? Hard cast WW, PC'ed and water quenched? Or try PP?

Thanks!
Well as you may know, PC is still in its infancy. 2yrs ago, nobody was dry tumbling or spraying. Piglet method was cutting edge technology and Hi Tek coating was only available from Bayou and not really any using it. I highly suggest you visit the "Coatings & Alternatives" sub-forum here. Some of us have varying degrees of success. I've personally shot 1" 100yd groups at 2K FPS with PC in the 30-30. I've pushed .223 past 2200fps recently and it's promising. Others have done more. I don't use anything other than PC now.

[303Guy]

The Lee Enfield seems to lend itself to paper patching. That said, I am looking at a plain cast boolit for one of my Lee Enfield's.

I haven't really looked into powder coating but it sounds like a lot of effort for small batches but worthwhile for large batches. That's just a perception which maybe wrong. If wrong I might look into it sometime.

I'm a fan of the heavy boolit to make up for lower velocity concept. I've shot 265 gr boolits but they are a tad long for magazine use. They work well on turkeys! Or were those 245 gr? Whatever they were, they had full penetration and left a big hole! They were actually intended for pigs but to make them more versatile I gave them a wide and shallow hollow nose for small fame. The theory being that the thin rim of the hollow nose would open up on small critters while leaving the boolit as a flat nose with penetration for pigs. I ended up with 194 gr boolits