45ACP Zero 185 JHP, 4.2 N310 Test Targets (25Y & 50Y)

Hello,

There is often a disconnect between a load that performs well at 25Y and one that performs well at 50Y. I don't have enough data to convincingly say, "If you get x size group at 25Y, you should see y group at 50Y," but I'm starting to put together enough to potentially make some heuristics that one can use to determine if they should continue down a particular load development path. Consider the below example:



A 100-10X group can easily become a 100-3X group. Or worse- and never better. But: in any case and this one in particular as it as rather famous load, either is still a 100, which is what we should be concerned with.

Looking at the groups, it would be easy for someone to look at both and consider them non-related. But of course they are the same group, captured at 25Y and 50Y. Breaking down our inclination that we have towards categorizing what we see with symmetry and instead categorizing for score is probably the first stepping stone to a better understanding of how we do or do not call shots.

Best,
Chase

thank you for sharing your observations. I find them very interesting.
if I understand you correctly when you say "they are the same group, captured at 25Y and 50Y", the same bullet penetrates the 25Y target and 50Y target. What are the effects of the bullet hitting/penetrating the 25Y target on its flightpath? Wouldn't that change something? Are we assuming that it is negligible? What would 10 rounds shot at 25 yards look like compared to 10 (different) rounds shot at 50 yards?

One issue is if these two groups were the same 10 shots fired on two targets, the 25 yard target can affect the results on the50 yard target.

An interesting experiment, Chase, and thanks for your effort.  Have you mapped a single bullet's impact at 25 and 50 yds?  The same experiment has been done with 22 LR at 50 and 100 yds on electronic targets, so there is no interference by the closer target on the more distant.  It is not necessarily a simple spread, and impact prediction not intuitive, as some bullet spiraling seems to occur.  I doubt hitting paper would significantly affect impact downline, but I have no data.

Again, interesting and I love experiments, but how do you think it might be actionable to make ammo (or guns) of more precision?

samtoast wrote:thank you for sharing your observations. I find them very interesting.
if I understand you correctly when you say "they are the same group, captured at 25Y and 50Y", the same bullet penetrates the 25Y target and 50Y target. What are the effects of the bullet hitting/penetrating the 25Y target on its flightpath? Wouldn't that change something? Are we assuming that it is negligible? What would 10 rounds shot at 25 yards look like compared to 10 (different) rounds shot at 50 yards?

Yes, you understand correctly. I am presently setting up targets at 25 & 50 to see if paper @ 25 makes a difference. No conclusions yet since it is early days for me. But, my intuition says a nearly half inch bullet isn't really getting tossed around when it hits paper when it is running right at 800 fps at that distance. In fact, what I plan to do is compare the different velocities at the relevant distances once I have enough data to see if there is any effect from the 25 yard target interfering/slowing down the bullets on the way to 50 (compared to targets shot with no 25 yard target on way to 50). Granted, it would be but one test and may be inconclusive, but I have thought about this issue and how you might try to see if it is really present.

At the moment, I am assuming it is negligible. I may come to believe otherwise in the future, once I have enough data to modify my view.

Thanks,
Chase

sharkdoctor wrote:An interesting experiment, Chase, and thanks for your effort.  Have you mapped a single bullet's impact at 25 and 50 yds?  The same experiment has been done with 22 LR at 50 and 100 yds on electronic targets, so there is no interference by the closer target on the more distant.  It is not necessarily a simple spread, and impact prediction not intuitive, as some bullet spiraling seems to occur.  I doubt hitting paper would significantly affect impact downline, but I have no data.

Again, interesting and I love experiments, but how do you think it might be actionable to make ammo (or guns) of more precision?

Right now I'm mostly trying to determine how best to repeatably set up my testing, issues I may run into, etc. It's early days for me, and I am certain there is a bit of a learning curve to climb through.

That said, I did think about mapping out the shots between the two targets using my spotting scope, and may elect to try some of that in the future. I agree that it is not necessarily a simple spread, and if I am giving that impression, I apologize. A way to capture what I am trying to tell the story about is looking at bigger groups- 30, 40, 50 shot composites- but again, cart and horse and all.

I've thought about how to use electronic targets for this, which would remove all doubt regarding 25Y paper impacts, and would certainly make data acquisition easier and faster. I don't know that the freEtarget can be scaled up for the window size I'd need. There are also considerations to address for how to get this done at the club I'm a member of- I would need to be able to move the apparatus back and forth so that some chucklehead doesn't come along and use a frame for shooting on. I've thought about making a rolling base, which would be the best way to move things around...

In any case, what I was trying to point out from the above targets was: let's say you called all those Xs at 25. Congrats, great job. Now, take the 25Y target away. Would you also have called them Xs at 50? How much wiggle room do top shooters have between saying, "I sunk that one," and "right side 10"? Maybe more importantly- did the ammo let them down, and if so, by calling their shots, how often do they say, "shot deviated from call- I performed correctly?"

It's the sort of stuff that, if you don't consider appropriately, can really do a mind job on your shooting. Food for thought, at any rate.

Thanks,
Chase

Just a refresher on the "Marine Load": https://www.ssusa.org/content/usmc-match-45-load/

Chase,

You have data that would give you an approximation regarding calling shots.  Consider the 25 yd target.  One could calculate the circular area of probability, mean radius, for n= 10.  A good approximation for 95% confidence could be made.  The geometric center is about dead on the X.  So- if you estimated your dot was dead center at the shot break you could call an X.  Now, what about a called break at 9 O'clock in the eight ring?  Draw a circle there, and it would likely show the shot could be a 7, 8 or 9 - just an estimate.  Of course at 50 yds, the 95% confidence interval is estimated in the same way, likely over twice as large, and thus more difficult to call an exact shot value.  It all depends on one's ability to pinpoint dot position at the shot break, and the precision of the gun and ammunition as estimated by circular area of probability.  Am I misunderstanding where you are trying to go with this?  If so my apology- I just finished a 2700 and am working on finishing my first tot of rum.

You understand quite well.

We are often told that we need learn to call shots, and to understand the feeling of a good shot. I don't disagree with this- it is something that you need to get good at if you want to do well in any shooting sport (archery, golf, rifle, etc). But here is the thing; if you don't actually have a sense of what a real group looks like from your equipment, you can call shots in error and have no idea you are doing so. This is the main reason I disagree with the notion that using a 3/4/5/6 inch gun is acceptable for beginners; it isn't that it can't be done, but if your equipment can move things around on you up to 4/5/6 inches, well, you aren't going to get better at calling shots. Of course, I'm aware of the challenges that arise from such a view, and don't wish to discuss them here.

I happen to believe that most groups that are presented on the forum- the knot hole bunch- do a mind job on folks. Nothing wrong with such groups- and they do occur in the wild in testing- but no human can shoot them with any sort of notion of routine. If they did, we'd see plenty of 100-xX from the AMU @ 50Y, and we don't. We look at these knot holes and appreciate the symmetry, and start to incorporate that vision as a representation of how we believe our shots are impacting. But that incorporation is a mistake- the chaotic nature of what we are doing means seeing groups like the one at 50Y above is much more realistic about what is happening in the day to day.

So when I say I'm interested in how people can say, "I sunk it, that's an X," and "this is a high X/10/9," etc., (and be correct!) what I'm getting at is that the level of people who can do that are AMU shooters and High Masters. I'm certainly not saying that for the rest of us we ought to give up trying to call our shots precisely- but that when we do call our shots, we consider the chaotic nature of what we are doing and accepting that. I don't believe most people consider this when learning to call shots (because they see knot holes in their minds eye)- and I'm hopeful that when they see targets like this, they can appreciate that both targets are still 100s, and that you can do everything correctly & to feel but still turn in a shot in the next higher ring, as almost happened here. Maybe if a butterfly just flew in a different direction in Madagascar it would have...

I am concerned with this particular edge or corner case because I recognized it as a stumbling block to better shooting for myself; and I know if it impacted me, it surely has done so for someone else. Hope saying this stuff out loud helps someone further refine their shooting game.

Best,
Chase

A perfectly called shot, can only be as good as the group size the gun/ammo are capable of. For ease of discussion. Let's say you have a gun/ammo combo which is capable of 2 inch 50 yd groups, then a perfectly aimed shot on the X and called as such, should be within 1" of the X. A called and executed shot at 12 oclock on the 10 ring should be within 1" of 12 oclock on the 10 ring. Obviously, the more accurate your gun/ammo the more accurate the shot will be relative to the call.

Too often, I have seen folks shoot guns which at best will shoot 4" at 50 yds. They call an X yet are stunned when the shot is a loose 10 or tight nine. Somehow we lose sight of the group capability limitation when the call and placement of the sights were perfect.

Interesting stuff!  Surprising to see that the 50yd pattern is not just an expansion of the 25 yd pattern.

Shot from a rest?

It seems unlikely that passing perpendicularly through a paper target would affect a bullet's trajectory this much, but as you suggest it should be tested.  A pass-through electronic scoring target would be best, but if it can't be arranged there may be another way: Shooting a number of targets at 50yd, half with targets overlaid at 25yd and the other half with no targets at 25.  The 50yd groups could be measured and means compared between with/without a 25 target (radial distance from center-X, etc).

Chase,

Thank you for your thoughtful response.We are thinking along the same lines.

If you look at the groups using angular measurements instead of looking at scoring or linear measurements, they are the same size.

I’d run this past Bryan Litz.  These bullets appear to be shooting a spiral track which is indicative of over stabilization.  If not, then there is an effect from the initial paper impact.  The reason I say this is that there are radial displacements on the target of the bullet relative to the  group center of the same shot between the two groups.  For example shots 4, 5, 7, and 8 appear to shift from the group center to a place diametrically opposite the group center.  It has been known for sometime that groups under 25 shots are notoriously unreliable due to the (at least) dual scatter present in projectile flight.  So I’m not surprised.  Both MD Waite and EH Harrison also found that ammunition grouping was proportional to range if the ammunition was decently assembled.  It’s just that most ammunition is barely adequate to begin with.  Even though the 25 yard group is all in the X, there is evidence of stringing. Not what I like to see.  I like to see a round blob well inside the X ring at 25 yards.  If my gun groups all around the x or stringing in another direction, then at least one of the mpbimodal dispersions is too large…

Bryan Litz.  https://appliedballisticsllc.com/

JHHolliday wrote:Interesting stuff!  Surprising to see that the 50yd pattern is not just an expansion of the 25 yd pattern.

Shot from a rest?

It seems unlikely that passing perpendicularly through a paper target would affect a bullet's trajectory this much, but as you suggest it should be tested.  A pass-through electronic scoring target would be best, but if it can't be arranged there may be another way: Shooting a number of targets at 50yd, half with targets overlaid at 25yd and the other half with no targets at 25.  The 50yd groups could be measured and means compared between with/without a 25 target (radial distance from center-X, etc).

Shot from a barrel tester.

I agree on the thinking about the 25Y paper- I mean, yes, sure, it probably has some influence. But I imagine it is much smaller than we all want to recognize. But that's the thing, right- let's test it, kick the data around, see what we think on the other side- if I'm wrong, I'll cheerfully admit it. Of course, people generally aren't interested in 25Y targets- if a load is good at 50, then it's good at 25, ipso facto.

It isn't like the bullets do some sort of cartoonish snake dance between either 25 and 50 where they all go down the same hole after dancing between distances. Because as we all know, that dance actually happens at 49 yards, which explains my long line targets looking the way they do.  

Best,
Chase

Wobbley wrote:... which is indicative of over stabilization. 

I guess my question then, is: "How fast does a 185gr bullet need to travel before it is over-stabilized in a 1:16 twist barrel?"

If you have a hypothesis, it can be tested.

Best,
Chase

As a former student of statistics I would caution against reading too much from a single experiment (N=1).  If you had dozens (or preferably 100s) of similar 25/50 dissimilar imprints, that would be an addressable quandary.

If you can, repeat it many times.

H&G bullet drawing indicates the #68 bullet is about .63 inches long.  With a BC of around .15.  Putting it into the Berger Stability calculator at 800fps, a 16 inch twist gives a stability factor of 8.  A 24 inch twist has a  stability of 3.7.  So if you could find a barrel with a 20 or 24 inch twist and repeat the test you might have some different results.

McGowan Barrels lists twists of 10, 16, 18, 24, & 36.  You can reach them at https://mcgowenbarrel.com/shop/full-custom-barrel/

JHHolliday wrote:As a former student of statistics I would caution against reading too much from a single experiment (N=1).  If you had dozens (or preferably 100s) of similar 25/50 dissimilar imprints, that would be an addressable quandary.

If you can, repeat it many times.

I don't disagree, have considered this in terms of cost, and appreciate the note. While I have you, I do have some stats questions that maybe you can speak to:

1) What number of shots would you recommend to have a meaningful confidence interval? My thought is 60, but willing to entertain a different figure if it makes more sense (95% should be good enough, understand it would be more for 99%)

2) Is there a particular group size measurement that you believe would lend itself to more robust results?

3) The plan is to use TARAN to build composite groups from 10 shot strings. Let's say I have 100 shots in a group, or 10 strings. Is there a good rule of thumb on how to compare smaller quantities of shots against the larger one? I guess Students distribution is good to some number before large groups take over... Put another way- let's say I have a well documented test barrel. All sorts of loads. When would be ideal, in terms of sample size, to reject/compare/analyze a small number of shots/strings/composite groups against the entire corpus, while having meaningful results?

Thanks,
Chase

It’s been done by this guy… https://youtu.be/JSxr9AHER_s

Was  also wondering about the paper at 25yds affecting trajectory.
I shot an M-60 at Ft. Lewis and remember seeing a tracer round the hit outside of the bull and seeing it fly off at around a 45 degree angle.
It most likely hit a part of a canvas backer, so not the same as a thin 25yd repair center.
A friend and I tested his 45 in a RR and found that 4.5grs of vv310 produced the best results.

Before you all go down the ballistics rabbithole, did Chase confirm that shot#1 @ 25 is #1 at 50 yds and so on, as shown on the Ballistics-X analysis?  The 50yd looks arbitrarily numbered - just asking.

Re: Group size, post hoc.

Null hypothesis:  Hitting a "paper target" at 25 yds has no effect on a 45 wadcutter group size at 50 yds under the conditions shown, as expressed in MOA

I will eyeball it and say the null hypothesis is not rejected, but I will leave it to someone else to do a proper statistical test!

sharkdoctor wrote:Before you all go down the ballistics rabbithole, did Chase confirm that shot#1 @ 25 is #1 at 50 yds and so on, as shown on the Ballistics-X analysis?  The 50yd looks arbitrarily numbered - just asking.

My thoughts exactly.

When this thread started, I looked at the targets before reading anything and it seemed evident to me right away that it was the same shots on two different targets.

The shot numbering on the 50 yard target sure looks erroneous to me as compared to the 25 yard target.

DA/SA wrote:

sharkdoctor wrote:Before you all go down the ballistics rabbithole, did Chase confirm that shot#1 @ 25 is #1 at 50 yds and so on, as shown on the Ballistics-X analysis?  The 50yd looks arbitrarily numbered - just asking.

My thoughts exactly.

When this thread started, I looked at the targets before reading anything and it seemed evident to me right away that it was the same shots on two different targets.

The shot numbering on the 50 yard target sure looks erroneous to me as compared to the 25 yard target.

The numbering on both targets is arbitrary and was done by me, not Chase. I was more interested in group size using consistent measurement between the two targets (measuring in MOA instead of inches/scoring rings). Matching shots at each yard line has no impact on group size. It’s roughly a 6.5 MOA group at both distances shown. 

If you look at the mean radius at 50 yards, with a 45 caliber bullet hole, that’s pretty close to X ring sized. 

I realize n=10 is a small sample size, but those results are pretty close.

I understand the skepticism on paper at 25Y distorting/interfering with 50Y groups. Early days, as mentioned. However, if all one needs is a single counterexample to demonstrate why the paper at 25Y isn't affecting the 50Y groups, then please look below.


Two things: 1) I understand that we live in a continuous world, and am not making any sort of claim that paper doesn't matter. Don't know yet. However, the picture seems to indicate that it doesn't seem to matter- both are 100-10X. 2) When looking at this photo, please don't refer to the bottom X on the 50Y target as a flier. There is not enough data to indicate that, and it seems to stretch bounds of reason to suggest that it is.

Best,
Chase