Analyze My Groups

Schmo

WKR
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Apr 29, 2023
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I’d like some input from you highly competent field marksmen. Finally getting to shoot some accuracy groups out of my 6 PRC. I guess it could be any reason, but at least some of these groups seem to me to be positional & inconsistency errors. I’d like to know if you think the same. Please note that each of these groups are a different handload, and not the same load. Thanks in advance!

IMG_6274.jpegIMG_6275.jpegIMG_6276.jpegIMG_6277.jpeg
 
I wouldn't call myself a highly competent marksman, but I'll play.

Groups should be round. Stringing indicates a rifle system or shooter positional problem.

5 shot groups have +/- 50% variation on extreme spread, and as shown in your photos they aren't enough to determine if you have a round group to adequately demonstrate the cone of fire.

Step your group size up to 10 shots (20 is even better if you have the time and components) and you'll get a lot more information. I wouldn't feel comfortable choosing a load with any confidence based on the groups above.
 
I wouldn't call myself a highly competent marksman, but I'll play.

Groups should be round. Stringing indicates a rifle system or shooter positional problem.

5 shot groups have +/- 50% variation on extreme spread, and as shown in your photos they aren't enough to determine if you have a round group to adequately demonstrate the cone of fire.

Step your group size up to 10 shots (20 is even better if you have the time and components) and you'll get a lot more information. I wouldn't feel comfortable choosing a load with any confidence based on the groups above.
I understand the 10 shot groups, and like to zero based off of 10 shot groups. These were after testing powder charge, and picking a load. Didn’t want to deal with 10 of each, because of cooling time (suppressor cover is ordered, but don’t have it yet, so mirage appears really fast). Basically, need a load to hunt with next week out to ~500 yards.

But the stringing made me think that shooter error was causing some of the large groups.
 
I understand the 10 shot groups, and like to zero based off of 10 shot groups. These were after testing powder charge, and picking a load. Didn’t want to deal with 10 of each, because of cooling time (suppressor cover is ordered, but don’t have it yet, so mirage appears really fast). Basically, need a load to hunt with next week out to ~500 yards.

But the stringing made me think that shooter error was causing some of the large groups.
Makes sense and totally agreed. It's painful enough for me to spend 30+ minutes to lay down and shoot a 20 yard zero group in 4 round intervals with cooling time between. I would really hate doing it multiple times with components swaps. It sounds like we have similar requirements for our hunting rifles, as I'm also a 500 yard max shooter with my current skill level.

I use Form's painless load development now and really like it. I'll try the bullet I want to shoot with 1 or 2 types of powder, and as soon as I get a 10 round group that sub 1.5 MOA and know I'm a grain or so under pressure signs, I'm done. Then I shoot a 20 round zero to make sure it's dead-on, which has the side benefit of giving me an even better understanding of the cone of fire. After that, I start walking out the distance to true the ballistic profile and I'm done with load development and rifle setup.

Are any of the 5 shot groups above the same load with no changes where they could be overlaid to get a 10 round group? To feel confident in my zero and cone of fire with only 5 rounds, I'd need a real tight shooting gun, (like a true 0.5 MOA for multiple 5 shot groups) and I haven't been that lucky or that good of a shooter yet.

If you don't have the time or components to go through this process before your hunt, I'd just limit myself to 300 yards personally. At that distance having a zero that's off by a tenth or two and DOPE that's off by a tenth or two is only going to have you off by 3-4 inches and won't be the reason you miss the vitals of a deer.
 
I don't shoot a 6mm but there should be a bullet/powder combo that is inherently accurate with that caliber. That's where I would start but with your time constraint you may not have the components. When you find that combination you'll see the potential immediately. For my load dev, I look at vertical and go from there. I start 10 to 20 off the lands, dependent on what everybody else is doing, and I don't mess with seating depth till I'm done and I know how it's shooting. Then I might try + and - .005 but that's the extent of it.


For reference, this is a 7 grain powder spread, 77 to 83 gr, right to left.
77-83 grains r to l (Small).JPG

this is the follow up
11-6-24 (Small).JPG
 
Are any of the 5 shot groups above the same load with no changes where they could be overlaid to get a 10 round group? To feel confident in my zero and cone of fire with only 5 rounds, I'd need a real tight shooting gun, (like a true 0.5 MOA for multiple 5 shot groups) and I haven't been that lucky or that good of a shot
No, but I can offer this. It’s probably completely irrelevant, but this is a composite group of the same brass, powder, and primer, with 5 shots being the 112 Match Burner, and 5 shots being the 108 ELD. The actual holes are 108 ELD, and the other 5 marked shots are 112MB. A composite group put together from two targets. Same exact aiming point between the two targets, and same impact point.

IMG_6285.jpeg
 
Overlay those groups and they are pretty round. Also appear to be ~1.3 moa extreme spread? If so, that is not bad accuracy.
 
You really can’t correlate anything specific from those groups. Looks like a decent gun, a decent shooter, shooting decent groups, with a variety of stuff. That’s literally all I can gather personally.

I would focus more on whatever produced the first target though. Looks promising.
 
How were these groups shot? Prone, bipod, bags, etc.?

Personally, I wouldn't gauge anything from groups shot from field positions until I had a full understanding of how the rifle shoots at it's best. Usually I do my group analysis/load dev from bags on a concrete bench, verify it follows suit prone with a bipod, and then practice from there.
 
How were these groups shot? Prone, bipod, bags, etc.?

Personally, I wouldn't gauge anything from groups shot from field positions until I had a full understanding of how the rifle shoots at it's best. Usually I do my group analysis/load dev from bags on a concrete bench, verify it follows suit prone with a bipod, and then practice from there.
Shot from a bench on a flat range. Rock Jr front rest, half filled bag for rear support. T3X with PBB 6 PRC prefit from a KRG Echo. Gonna put it back in my Stocky’s VG
 
Shot from a bench on a flat range. Rock Jr front rest, half filled bag for rear support. T3X with PBB 6 PRC prefit from a KRG Echo. Gonna put it back in my Stocky’s VG
Off a bench I would say if you felt good about clean breaks on every shot, that's just how the rifle shoots those loads and the groups don't seem to be affected by positional inconsistencies.

For my personal standards, those groups are unacceptable. The statistics on how much they'll grow with sample size lead me to believe that would probably be a 2 MOA+ cone of fire. It's possible that you captured the ES of the groups within the first 5 shots and the next 30 would fill in, but not probable. I would either continue testing, or perfect zero with a large sample size and see if the result inspires confidence.
 
Off a bench I would say if you felt good about clean breaks on every shot, that's just how the rifle shoots those loads and the groups don't seem to be affected by positional inconsistencies.

For my personal standards, those groups are unacceptable. The statistics on how much they'll grow with sample size lead me to believe that would probably be a 2 MOA+ cone of fire. It's possible that you captured the ES of the groups within the first 5 shots and the next 30 would fill in, but not probable. I would either continue testing, or perfect zero with a large sample size and see if the result inspires confidence.
I felt great about some of them, knowing where my crosshairs were when the shot broke. Some others, not as much.
 
I also don’t like the KRG Echo on that rifle. It recoils more than the much lighter Stocky’s VG.
 
5 shot groups have +/- 50% variation on extreme spread...
They have a lot more variation than that, when you look at large samples of 5-shot groups.

I'm a physicist, not a coder, but in a simulation I coded, for example, I used 20,000 5-shot groups and Gaussian distributions of shot placement in two axes of a plane, and I get the smallest group being 0.208 MOA ES and the largest being 2.959 MOA ES. Mean group size is 1.229 MOA ES, for reference.
 
Analyzing and optimizing precision is mainly about controlling and eliminating variables. Make sure you're using good bench technique (use a solid bench and good bags) and shooting fundamentals when testing your rifle/load for POI variation. That way you can be reasonably sure that any variation is caused by the rifle/load system, and not your shooting form or supports.

The purpose here is not training the shooter, it's analyzing your rifle/load performance, which is done by removing shooter and shooting setup variables from the equation as much as possible.
 
Analyzing and optimizing precision is mainly about controlling and eliminating variables. Make sure you're using good bench technique (use a solid bench and good bags) and shooting fundamentals when testing your rifle/load for POI variation. That way you can be reasonably sure that any variation is caused by the rifle/load system, and not your shooting form or supports.

The purpose here is not training the shooter, it's analyzing your rifle/load performance, which is done by removing shooter and shooting setup variables from the equation as much as possible.
Unfortunately this shooter very much needs trained! 🤣
 
Check out Erik Cortina on youtube. He has a video with Jack Neary about analyzing groups that is informative.
Don't do this.

Change bullet, powder, primer. Pick 1-2gr under book max for each combo. Shoot 10rds into one bull for each, no arguments. Measure MV while you do this. Pick the combo that performs the best for your needs. The end.

I don't bother stomping on powder charge anymore, unless it gets me to the next wind number. I don't bother with small tweaks on powder or seating depth, it has been proven this will not make any difference in precision and consistency.

Use the best components if you want the best results. For me that's Berger bullets, Lapua or ADG brass, CCI or FED primers, Hodgdon or VV powder. Not saying others won't perform, just saying that's what I've personally seen give the BEST precision.

If you doubt your own ability to shoot 10 shots precisely, you shouldn't be worried about the gun. Train with a precise 22 or some other known good rifle/ammo system until you don't have any doubt in your own abilities to shoot 10rd groups consistently with high precision. Not saying you won't still pull shots, but you'll know when you do or when your position is compromised and you aren't getting maximum precision.
 
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