RPM Test; a tale of three twists, Chapter 2

[leftiye]

So, when you add ten grains of powder to an accurate load, and fire it in a too tight twist does it stabilize at all, or just fly off into never never wherever? Did it lose accuracy, or did it not ever have it to lose. There's your straight question Larry, let's see if you can stay on subject.

[leftiye]

So now it's everybody'd RPM theory. Isn't that convenient!

[BABore]

I would like to see the same test using bullets lubed with LBT Blue. I can guarrantee you that if I changed to 50/50 Alox-beeswax lube on one of my accurate HV loads, it would shoot all over the place. Drop the velocity and that can easily change things. This I know cause I have done it. Even more or less similar lubes can change the result drastically when shot side-by side. It seems like your purposely throwing a monkey wrench in the mix when you just simply add more powder and expect to prove something. It just don't work like that.

[Larry Gibson]

Leftiye

About time you got around to asking a straight question.

Yes the bullet was stable. That was well documented through out the Chapter 2 test. The measured BCs demonstrated this. Were the bullet not stable the BCs would have not been as consistent as they were with all three barrels. The 10" twist with this load faired no worse than the other two twists. While the accuracy was not good the "10 gr more load" exhibited exactly what Bass said it would if RPM was the culprit when he proposed this last test. That was that the bullet would lose accuracy in a larger non-linear fashion. That is exactly what happened with this test of the 38 gr load.

Since a 171 gr bullet is in the middle of the stability spectrum for a 10” twist barrel at 2500 fps I’d not say that it was not stabilized at all or that it never had stability. The reasons for this are there was no leading in the bore to indicate stripping and the bullet holes are nice and round all the way to 200 yards. Nothing there to indicate the bullet was unstable. Obviously from the accuracy of the 28 gr load the bullet had the accuracy capability. Thus it is my contention that something was affecting it’s accuracy during flight. That something is RPM.

Now if we look at the 28 gr load we see that it's RPM is still within the RPM threshold and it has not yet reached the point where the RPM are overcoming the rotational stability. Thus it's accuracy is linear throughout the test. The 38 gr load is well above the RPM threshold and it is obvious the RPM is adversely effecting it's accuracy in a very non-linear way.

We have discussed previously that the bullet may still be stable yet is cork screwing around its flight path. Apparently that is what is occurring. More testing would be required to confirm that. The bullet at some point down range may actually become unstable and fly off into “never never where ever”. Perhaps this is what’s happening to Bass’s bullets(?). I’ve never actually shot a load that was shooting this badly at 200 yards any farther away so I can’t say. I have seen other bullets go awry the same way though so I suspect instability at some point down range is the reason in this case also.

Yes it is “everyone’s PM theory”. The facts are simply there. Drive a regular cast bullet above it’s RPM threshold (that threshold is in the 125-140,000 RPM range for most cast bullets) and inaccuracy in a non-linear fashion is the result. As to it’s “convenience”, I’d say it is damn well pretty inconvenient! I would much prefer to drive this 311291 at 2500 fps with 2 moa accuracy out of any .308 or ’06 all the way to 500/600 yards. It just isn’t going to happen is all. RPM is the reason why.

Larry Gibson

BTW; you will probably come back with "more oatmeal" etc, ad nauseum saying I've avoided your question. I actually expect that. However, I have answered your question(s) and everyone will see that. If you don't like the answer that is fine. Kindly say why and give some sort of facts to back up your disagreement. Otherwise everyone will see your response for what it is.

[Larry Gibson]

I would like to see the same test using bullets lubed with LBT Blue. I can guarrantee you that if I changed to 50/50 Alox-beeswax lube on one of my accurate HV loads, it would shoot all over the place. Drop the velocity and that can easily change things. This I know cause I have done it. Even more or less similar lubes can change the result drastically when shot side-by side. It seems like your purposely throwing a monkey wrench in the mix when you just simply add more powder and expect to prove something. It just don't work like that.

BaBore

10" twist .308s are rather common as are 311291 moulds. Why don't you just conduct the test yourself?

However, I will be testing the effects of different lubes later on in the RPM test I am conducting (doesn't anyone read what I post or are some just jumpimg to erronious assumptions?). FYI; I have used LBT Blue in the past and found no difference in accuracy with regular cast bullets compaired to Javelina up through 2600 fps. So I actually already have performed your test although it was with an '06 and 311291 and 311299.

In the continuing RPM test I will be testing Lar's lubes including his Carnuba Red, BAC and 2500+. If you want to send me a tube of LBT Blue I'll try that too. PM me for the address.

Larry Gibson

[leftiye]

[We have discussed previously that the bullet may still be stable yet is cork screwing around its flight path. Apparently that is what is occurring. More testing would be required to confirm that. The bullet at some point down range may actually become unstable and fly off into “never never where ever”. Perhaps this is what’s happening to Bass’s bullets(?). I’ve never actually shot a load that was shooting this badly at 200 yards any farther away so I can’t say. I have seen other bullets go awry the same way though so I suspect instability at some point down range is the reason in this case also.] Larry gibson.

Larry, Have you yet figured out how a boolit flying point-on could fly in a spiral ?

This which is quoted above is exactly what I had in mind when I postulated a boolit being unstable from the beginning of it's flight. It may be semantics, but I don't see corkscrewing as being stable (kinda violates the defintion, doesn't it?). Plus, while Ballistic Coefficient might detect cork screwing (though cork screwing might have to be quite substantial before the time of flight was changed enough to pick up), it wouldn't detect simple inaccuracy as the boolit that is truely stable (not corkscrewing) only travels about .001," (maybe less) farther at 100 yds. to make a 4 or 5 inch group (or much bigger) than would one printing a perfect one hole group (trigonometry - with two legs of a right triangle 100 yds. in length, one diverging from the right angle at that distance by 2"). Do you have any idea how much farther a boolit would have to travel before it would show up in the B.C.? Might be quite a ways at 2500 fps.

It would seem to be necessary in any theory that the earlier flight of a given round would exhibit unstability if the later flight were supposed to get worse. However, both Bass's theory and yours do show ways for a stable boolit to become unstable. As always, the question is, "how did it get unstable?" Supporting issues are those that exacerbate the instability (again, by definition - if something makes a pre-existing condition worse it isn't the primary factor. ).

[Larry Gibson]

Leftiye

Larry, Have you yet figured out how a boolit flying point-on could fly in a spiral ?

Hard to describe but if the center of gravity does not coincide with the center of form (this is true of most bullets in flight, again it is why we shoot groups instead of one hole) as the bullet spins the centrifugal force causes the bullet to corkscrew or rotate around it's axis of flight. It appears that this is what begins to happen when the bullet excedes it's RPM threshold. It also appear that the bullet is able to fly point on for a distance then it becomes unstable somewhere out there. Further testing could prove or disprove this line of thinking. I may get to it down the road.

This which is quoted above is exactly what I had in mind when I postulated a boolit being unstable from the beginning of it's flight. It may be semantics, but I don't see corkscrewing as being stable (kinda violates the defintion, doesn't it?). Plus, while Ballistic Coefficient might detect cork screwing (though cork screwing might have to be quite substantial before the time of flight was changed enough to pick up), it wouldn't detect simple inaccuracy as the boolit that is truely stable (not corkscrewing) only travels about .001," (maybe less) farther to make a 4 or 5 inch group than would one printing a perfect one hole group (trigonometry - with two legs of a right triangle 100 yds. in length, one diverging from the right angle at that distance by 2"). Do you have any idea how much farther a boolit would have to travel before it would show up in the B.C.? Might be quite a ways at 2500 fps.

Yes it is obviously a matter of semantics. I think of a bullet being "unstable" when it either hasn't enough RPM to achieve stability or wobble, yaw and pitch are excessive. In the case at hand we know that the bullet does have enough RPM to be rotationally stable. We also know by the consitent BCs that wobble, pitch and yaw are not excessive. Something else is happening. The tests are showing that RPM, at a certain point, has a very detrimental effect on a regular cast bullets accuracy. What exactly is that effect and how it works are what we are learning.

Perhaps you are right and this cork screwing effect is not "stable" in the larger text of the definition. Still it seems the bullets are flying point on to a certain point. I further think that as the corkscrew gets larger and larger the bullet does get unstable with wobble, yaw and pitching happening to the degree that the bullet sails off into never never where ever as Bass describes. Bass figured it was between 200 and 400 yards that it was happening. I don't doubt that based on the 14.5" group I was getting at 200 yards I'd guess the 311291s I was shooting at 2500 fps would be unstable very shortly after that. Perhaps they already were going unstable at 200 yards (?). The LBT bullet bass uses is much better designed for HV so I would expect it to go further before it went unstable. It appears that assumption is correct.


It would seem to be necessary in any theory that the earlier flight of a given round would exhibit unstability if the later flight were supposed to get worse. However, both Bass's theory and yours do show ways for this to possibly come to pass. As always, the question is, "how did it get unstable?" Supporting issues are those that exacerbated the instability (again, by definition).

Again we agree. Unstable is a condition of flight. The bullets may be imbalanced in the barrel but they are stable as they are restrained by the barrel. When in flight they are then unrestrained. In order for the imbalanced bullet to become unstable (given a sufficient twist for stability which we have here) something must act upon those imbalances. It is the effects of the centrifugal force caused by RPM that acts upon them. At some point the centrifugal force over comes the rotational stability. This is the area I refer to as the RPM threshold. Before that point the rotational stability of the cast bullet keeps it accurate. It was very obvious that this happens early in the bullets flight as exhibited by the 2.5" 50 yard group of the HV load. As the range increased so did the adverse effect in a very non-linear manner. Again I think we are in agreement here.

Larry Gibson

[Tiger]

I would like to see the same test using bullets lubed with LBT Blue. I can guarrantee you that if I changed to 50/50 Alox-beeswax lube on one of my accurate HV loads, it would shoot all over the place. Drop the velocity and that can easily change things. This I know cause I have done it. Even more or less similar lubes can change the result drastically when shot side-by side. It seems like your purposely throwing a monkey wrench in the mix when you just simply add more powder and expect to prove something. It just don't work like that.

I feel like super delegate when I say I endorse what BABore has to say.
Larry aside from the bullet lube is one most important things in shooting cast bullets. Before you go off I am not making accusations just saying what you already say...try different lubes beside the good 50/50 you have been using. Myself I never tried HV loads with 50/50 to start with.

Ralf

[leftiye]

How about we go with the (I think) standard definition - stable is rotating around the boolit's axis, no wobble. Any wobble, however typified is a degree of instability. It's not required to be in flight, it could be spinning stably on it's nose (or wobbling). It's about the boolit, not about flight. And if it becomes unstable the moment it becomes free of the barrel, it isn't rpms, it's either a deformed boolit or a bad launch. Rpm hasn't had time to do anything yet.

And once it becomes unstable, air resistnce can act upon the boolit to further unstabilize it.

You just can't assume that the B.C.s are ruling out a yawing or other minor instabilities. Nor can you say that it precludes deformations of the boolits. We all know these deformations are happening. It's one of the facts of reality. I've been at this since you first posted your test (I WILL add - with no answer from you). Things like this that threaten to unravel your whole test cannot be let go by, nor be ignored if you want in the end to claim a valid test.

[Larry Gibson]

Ralf

It's been in the plan from the beginning.

Larry Gibson

[Larry Gibson]

Leftiye

How about we go with the (I think) standard definition - stable is rotating around the boolit's axis, no wobble. Any wobble, however typified is a degree of instability. It's not required to be in flight, it could be spinning stably on it's nose. And if it becomes unstable the moment it becomes free of the barrel, it isn't rpms, it's either a deformed boolit or a bad launch. Rpm hasn't had time to do anything yet.

I can live with that definition.

Don't understand the nose part?

Instability can be caused by other things, i.e. a bad crown, etc. However, if the bullet exhibits the same BC as another same bullet fired out of a slower twist then the stability is the same. That the slower twist gives proportionall better accuracy at HV is telling us it is not because the faster twist bullets are damaged more or launched badly.

The effects of RPM on the HV bullet began very close to the muzzle as evidenced by the 50 yard group size and the continued larger size of the groups at 100 and 200 yards. It is a cumulative effect which is why the groups open at a non-linear rate.

Now I did admit to 3 "bad launches" in that test and called them. The rest were all good launches. Note the group sizes of the 28 gr load; a 2.5" 9 shot group at 200 yards ain't to shabby for a sporter rifle shooting cast bullets.

And once it becomes unstable, air resistnce can act upon the boolit to further unstabilize it.

Quite correct but that is if we have a really unstable bullet. We have no evidence of that as the computed BCs at 100 yards show.

You just can't assume that the B.C.s are ruling out a yawing or other minor instabilities. Nor can you say that it precludes deformations of the boolits. We all know these deformations are happening. It's one of the facts of reality. I've been at this since you first posted your test (I WILL add - with no answer from you). Things like this that threaten to unravel your whole test cannot be let go by, nor be ignored if you want in the end to claim a valid test.

Well, I'll tell you what I told you at the beginning since you were there. Yes we can assume that BCs tell us of yawing or other minor instabilities. Yawing, pitching and wobble along with all the other instabilities adversely effect the flight. They do that by causing the bullet to not fly as efficiently through the air. The efficiency of the bullet to fly through the air is measured by time of flight lost over a measured distance and compared to a "standard model". I measured the time of flight and the M43 computed the BC based on a G1 model. It is a measurement to the third decimal. Small variations can and are noted. We can see when the BC goes south so does the accuracy. The problem here is the BCs didn't go south but the accuracy did. The accuracy went south to a much greater proportional degree with the faster twist. The BCs remained the same between the twists when that accuracy went south. That tells us the stability of the bullets was the same and something else was causing the inaccuracy. Quite simple actually.

Another thing to remember is that the BCs of FN and RN bullets will decrease (most often) as velocity is increased. In the case here the BCs decreased at the same rate with each twist. Yet the accuracy decreased to a much greater proportional degree with the faster twists. That does not "threaten to unravel your whole test". Quite the contrary; it substantiates the test and the evidence that RPM is the culprit. I have not ignored it at all. The BCs are graphed out and studied in comparison with the other data.

The simple fact is; given two like bullets at the same velocity with one being more stable than the other, the more stable bullet is more efficient in flight. It will arive at the target quicker with less velocity loss. The more stable bullet will have a higher BC. The less stable bullet with have a lower BC. It is measureable and I measure them.

Exactly how do you measure BCs? Can you tell me it can't be done based on your experience?

I would like answers to the above two questions please.

Larry Gibson

[leftiye]

Larry, a fine treatise on practical Ballistic Coefficients.

No one said that B.C.s couldn't be measured. What I said was that given the propensity of boolits to cover distances quickly, even your quartz clock in your computer can't differentiate the differences in time between a perfect boolit flying at the axis of the line of fire from one with minor to maybe moderate deviations. You're right, the deviating boolit will at some point show up in decreased B.C.s, but at what amount of elapsed time will the computer and the program actually register a difference. And how much farther will the boolit have to travel in order to accomplish this?

As I pointed out a stable boolit would be clear off of your screens in POI before it traveled more than a thousandth or two of an inch longer distance than the one which impacted the center of the target. Your machine probly cannot measure the TOF at 2500 fps to travel .002"? Again, How much wobble, yaw, corkscrewing, or just screwing around does a boolit have to do before TOF becomes stretched out enough to affect your machine's B.C. calculations? It isn't even that black and white. How much longer TOF is necessary before it changes something with that program (B.C. number to the third place)?

As for the two questions you asked - so you can't say I'm not answering your questions. I don't measure B.C.s. And it's got nothing to do with my experience. We're talking about YOUR machine here. The distance that a boolit will travel can be calculated from the velocity and the minimum unit of time your machine will calculate. Then one can calculate how much of a spiral would have to be flown to add that much TOF to a given boolits flight. That would give you the minimum deflection (other than straight line) that will show up in your calculations. Perhaps easier, and more accurate still, take the minimum time change that will affect the B.C. as per your program, and calculate from that.

No, You CAN'T assume stable boolits, and no deformations because of B.C.s not showing a variance. You maybe correct in your assumption, but as you've said (I think) "Assumptions don't cut it." Not even yours.

[runfiverun]

note larrys 2.5" 200 yd group would be dead linear with the results i have had so far.
at 50 and 100 yds,
i will get the 200 yd group shot hopefully this week.
bass's prediction of the hv group going bad somewhere after 200 [never,never land]
is exactly tthe results i got when shot at 300 notice i only found 4 shots on a 4'x4' board.
i would think that this qualifies as neverland.

where do i get this LBT blue at maybe i will try the 37gr load again?
think i will need a boolit harder then4/6 mix? should i water drop some?

and i think larry needs a nap........lol

[Larry Gibson]

runfiverun

You got that right! A drink too!

Larry Gibson

[Larry Gibson]

Leftiye

So ok, let’s talk about “my Machine”, a M43. What is it do you know about it? Do you know haw fast it measures and how it computes BCs? How long have you been designing and or engineering chronographs and computers? Please tell us how you can be so emphatic that the M43 can’t measure BCs quick enough?

You are wrong in your opinion and assumption on the capability of the m43 to accurately measure subtle changes in BCs. Again remember the BC is derived from a loss of velocity over a specified distance. This is then compared to a “standard model”.

Below is the result of a 10 shot string of m118 fired in this rifle. I’ll list the velocity, the remaining velocity (284 ft), fps loss and the BC.

2661/2473/188/.476
2664/2475/189/.475
2641/2458/183/.487
2648/2459/189/.474
2656/2474/182/.494
2677/2489/188/.478
2673/2485/188/.479
2646/2462/184/.486
2661/2472/189/.474
2676/2491/185/.487

The 10 shot string had a muzzle velocity of 2630 fps with an ES of 36 fps. The ES of the BC (average .481) was .020. The velocity loss ES of the 10 shots was only 7 fps with an average of 185. So for every 1 fps difference in velocity loss there was a .0033 change in the BC. The group size was 1.925”.

Conversely a 10 shot string with the same M118 ammunition out of the 12” twist gave an average BC of .517 with an ES of .016, a muzzle velocity of 2644 fps with an ES at the muzzle of 42 fps, an ES for the velocity loss of 6 fps with an average of 172 fps loss. For every 1 fps difference in velocity loss there was a .002666 change in BC. The group size was 1.025”.

In both cases the computer rounds up the BC to the third decimal point as that is "industry" standard and just plain keeps it manageable. As it was aptly put but the designer and builder, Dr. Oehler; "the third decimal point on the BC is equivelent to asking; is the deer 191 or 192 yards away?". However, the third decimal is there and it certainly gives us an incite into subtle changes in a bullets flight.

That’s pretty close measurement to me but then I don’t have a PHD in mathematics, do you?

But let’s be practical and look at it this way; same ammo out of two rifles, one with a 10” twist and one with a 12” twist. The 10” twist gives a BC of .481 and the 12” twist a BC of .517. The 10” twist shoots a 10 shot group of 1.925”. The 12” twist shoots a 10 shot group of 1.025”. The worst BC also has the largest group. The group with the Best BC (largest) also has the smallest group. The smaller (worse) BC tells us that the bullets out of the 10” twist are not as stable as the same bullets out of the 12” twist barrel and should not be as accurate. Lo and behold, they are not! Amazing how that works.

Larry Gibson

(now I really do need that drink!)

[Larry Gibson]

Leftiye

Like I said I'm not a PHD in math but I think you need to double check your math. If the radii of the corkscrewing bullet is 2" from the axis of flight at 100 yards then that is the divergence at that range. A .001" divergence of a 10" twist (the divergence of a cork screwing bullet is around the axis of flight) and if it diverges .001" per revolution it is only .36" at 100 yards. Anyone who is familiar with calculating sight adjustment of iron sights can tell you that. That is hardly "off the screens" as you put it.

Perhaps I'm not understanding what your math problem is supposed to represent? The bullets actually diverge 1.25" (from center of group) at 50 yards, 2.35" at 100 yards and 7.75" at 200 yards. That divergence is evidenced by holes in the paper, not abstract theory. Whether or not they were cork screwing I can not say for sure. That remains to seen by testing. One thing for sure though, those bullets were stable at least at 100 yards with a very non-linear divergence.

Larry Gibson

[leftiye]

Yep, you don't understand. Nobody is hammering your machine, I'd love to have one like it. I'm not saying it is inadequate at all.

Maybe let's look at your data about es. of B.C.s How far can one of those boolits fly in the elapsed time differences between those B.C.s?

I'll go back to my illustration of stable boolits (completely stable, not corkscrewing) that are perfectly accurate that for some reason make a 10 " group at 100 yards (and for purpses of argument we will lie and say that they're still going through your chrono screens). What is the time of flight differential for the ones 5" off the orange patch versus the one in the center of the targ dot? If you do a trigonometric (I'd have to look it up to be able to do it) calculation of those that are 5" to the right versus the one in the center, you would probly find it has only traveled a few thousandths of an inch farther than the one in the center did. Not knocking your machine, but how long does it take that boolit to travel a couple of thousandths of an inch? Most certainly they will give identical B.C.s, and let's put it this way - virtually nothing could read the difference in their elapsed time (it's about twelve mllionths of a second, probly way less). Yet they're all over h@!! accuracy wise!

Nothing will register a change in B.C. until the difference in elapsed time exceeds the smallest time that makes a difference to your computer. How far can a boolit travel in that time? You have to answer what the smallest increment of time that your machine can read is, MORE importantly what is the smallest unit of time your program is prepared to notice (reads makes a diff. in B.C.)? Then we can compute how far a boolit can travel at 2500 fps. in that time span. Then we can (with some help) calculate how big of a spiral would be necessary to divert the boolit that far. Then we will know how much (cork)screwing around a boolit can do before your machine notices it.

Then we will have a picture of just how stable those boolits are or aren't. More correctly we'll know how unstable they can be before we know anything about it.

[Larry Gibson]

Leftiye

Me thinks you spend too much time at a keyboard instead of behind a rifle. You took a broad swipe at the "machine; "even your quartz clock in your computer can't differentiate the differences in time between a perfect boolit flying at the axis of the line of fire from one with minor to maybe moderate deviations."

"Nothing will register a change in B.C. until the difference in elapsed time exceeds the smallest time that makes a difference to your computer." Just how is it you know this for a fact? My guess is you don't because the M43 is quite capable of making those measurements. This is just another assumption on your part in a vain attempt to stave off admitting you are wrong. Unless you can come up with some documented evidence showing the M43 is incapable your reasoning is flawed from the get go.

You are wrong and you are confused. The M43 can and does do it. I gave you ample proof of that. Now you too want to renege and say oh hey golly gee I wasn't hammering your machine....like hell you weren't. I've given you the velocity lost figure for each round. That is the the measurement of time of flight. The more velocity lost the longer it took the bullet to get there. That answers your question on how long it takes the bullet to get there. Coincidently the more velocity lost the lower the BC. The M43 measures the time of flight in microseconds. Since you're not bragging up your PHD in mathamatics I guess you don't know what "microseconds are". You might try a Google search and find out.

How you equate .001" to be 5" at 100 yards still mystifies me (and I'll bet anyone else reading this) . Just what the heck are you trying to say? Perfectly stable bullets that are perfectly accurate do not give 10" groups. The point we're looking at is that Inaccurate bullets can fave rotational stability. Rotational stability simply means they are flying point on. It does not mean they do not have any yaw, pitch or wobble. All bullets one or a combination of them during flight. Rotaional stability does not mean the bullet is accurate. It only means the bullet is stable in flight and is not tumbling off to never never where ever. It does not mean that the flight of that bullet is straight and true. Take a .30 cal match bullet; out of one rifle it shoots 1/2 moa at 600 yards and out of a like rifle it shoots 3/4 moa at 600 yards. Are you then saying the 3/4 moa bullet is unstable?

All bullets have some degree of instability; they all have yaw, wobble or pitch or some combination. This is why we shoot groups instead of one hole. What we are discussing here is how bullets that are stable are also inaccurate. That is not an uncommon occurance even among jacketed bullets. Most military FMJ bullets being a good expample. Now let's get back to RPM and what is going on.

We know we have stable bullets out of the 10" twist barrel. Not perfectly stable but as stable as the same bullets at the same velocity out of the 12 and 14" twist barrels. The M43 measured the BC quite accurately. So what causes the same bullets that are capable of 2.5" groups at 200 yards at 1900 fps to go to 14.5' groups at 2500 fps? If the bullets were deformed it would, in fact, show up in a reduced BC. It didn't. If it was a "bad launch" then were saying I only "launched" the HV load badly? Considering the size of the 28 gr loads groups I think not. Considering the proportionately non-linear increasing size of the 38 gr loads groups, I think not. It remains obvious what is causing the inaccuracy; it is RPM. At some point within the RPM threshold that bullet at a certain RPM begins losing accuracy not stability. At that point accuracy, not stability, is lost in a non-linear fashion. At some point past 200 yards I believe the bullet also loses stability and will fly off into never never where ever.

BTW the M43 also prints out the time of flight in microseconds. They ran from 111132 to 109774. That's a difference of 001358 microseconds over the 10 shot string. I guess the time of flight is nice to know but it's actually the loss of velocity that is important. As in the example I gave of the M118 fired in two rifles, 10" and 12". The velocity loss was less with the 12" twist barrel. Ergo the BC was higher and the group was much better. Those are facts old boy. If you don't like them refute them with facts. But then you'd have to actually conduct a test by shooting a rifle instead of just pound away on your key board.

"Test results are nice, a brain is necessary. " Why don't you be "nice" and show us some test results?

I'm going shooting tomorrow, what are you doing?

Larry Gibson

[runfiverun]

larry
what i think leftiye is saying here is that a boolit [flyer] that is out of the group
has travelled an additional distance of .01.
and you showed that the m-43 measures this in time of flight? yes.

[Larry Gibson]

larry
what i think leftiye is saying here is that a boolit [flyer] that is out of the group
has travelled an additional distance of .01.
and you showed that the m-43 measures this in time of flight? yes.

Ok, so let me get this straight. The flyer in his 10" group flies one hundredth of an inch farther over 100 yards....and he wants to know if the M43 measures that? Is there a relevance to this? Is this the "how many angels can dance on the head of a pin question? We are talking a 10" group here right? And Leftiye is concerned about .01" additional travel? Over 100 yards? Well, all the bullets time of flight were measured. I did not track the hits on the target in relation to TOF or BC. However I did notice that most of those that were the flyers had the lowest BCs. Now if Leftiye is claiming the .01" extra travel as the reason the BCs are lower then he has really taken this from the sublime to the ridiculous.
Can the M43 measure that .01”? Maybe, maybe not, I really don’t know, what does it matter. All the bullets that were tested for BC in the Chapter 2 test went through the window of the skyscreens. Besides, if the bullet is a flyer 5” out then it is still a flyer 5” out whether it travels .01” extra or not. Is that deer 191 yards away or is it 192 yards away? What is the relevance to this?

Leftiye has made his stand. Nothing said is going to change his mind. He must continue to justify his position. When I started this test I said if the evidence proves the RPM threshold wrong I would admit it. Leftiye will not admit to anything. He is just hallucinating any kind of idea he can think of to discredit any test. He has failed to provide any data or documentation of his own that refutes the results of my tests or others tests.

I really don’t think I’m going to waste anymore time on his crap. I’ve said this before but I had hoped he would be reasonable. He didn’t have to agree but he should be reasonable. .01” extra travel at 100 yards….give me a break! Leftiye don’t even bother responding with more of this idiotic garbage.

Larry Gibson