testing load accuracy

[cpa5oh]

I tried shooting groups with my arms supported on my shooting bag to test accuracy of 9mm minor loads I'd been using in matches...and the result was awfully inconsistent. So I bought a rest.

Question - at what distance, using the rest, should be be shooting to best test the accuracy/point of impact of my loads? 25 yards? Multiple distances such as 10 AND 25 yards? Seems to me that the further out I get the more my human error is going to come into play...

[superdude]

Accuracy at 25 yards (traditional). Point of impact at multiple ranges in case you need to make sighting corrections for those ranges - even up to 50 yards (or greater), especially if the matches at your range set targets at that distance from time to time. It's good to know where the bullet will hit at whatever distance you might be required to shoot.

Yes, the greater the distance the greater the human error factor comes into play. It's unavoidable.

[Sandbagger123]

my range has 7 yard/50 feet /25 yards. i do initial zero at the 7 yard. then i check to see where they hit at the other distances, i also take the time to fine tune the zero. know where your gun shoots a different distance is very important in the gun game. a 8" peice of steel is pretty small at 20 yards and know where your gun hit at that distance will help a lot.

For me, i like my gun to hit at the top of the blade at 50 feet. it will be about a inch high at 25 yards. anything closer, just cover target with the blade.

[Flexmoney]

Benos has an old post or two around on his technique for shooting off of bags/bench. Maybe we can find it and link it in here...

Group shooting distance is going to vary from individual to individual...per their current skill level. I always suggest using a distance that matches your ability to shoot a decent group. That might be 5y...it might be 50y.

[ETA] found a link to the Benos technique for shooting off a bench with bags.

[bigedp51]

For you older folks I read the post by Brian Enos linked above and had to Google the term "dust cover" or the forward part of the frame in front of the trigger guard.

Edited August 29, 2013 by bigedp51

[Steve RA]

We older folks already knew what a "dust cover" is/was !!!

[Powerslide91]

I have been trying to figure out a good way to develop loads as well... Tried braced on a shooting bag, made my own angled rest like I saw in the Dawson videos... still always seemed to be some varibility I didn't expect... I have also personally found that my eyes are not a sharp as they used to be, so perfectly aligning on a small bullseye style target at 25+ yards was getting difficult and probably adding more variability to my numbers than anything.

Now I basically shoot mulitiple 5 shot groups at 20y freestyle on a target I made. I normally calculate the group spread for all 5 shots, and for the 4 best. I figure that way I can compare all my data and not need to try to remember if I shot a flyer in one group or not. I also try to shoot the same test build in at least 2 range sessions to figure if I was just having a bad day or not.

I consider it directional for load development. I mainly shoot multigun and some USPSA, so the difference in a 1" group and a 1.2" group isn't going to make or break my match.

[Flexmoney]

I have also personally found that my eyes are not a sharp as they used to be, so perfectly aligning on a small bullseye style target at 25+ yards was getting difficult and probably adding more variability to my numbers than anything.

Great point. You need a good target. I often like one of the grid targets found here: http://www.mytargets.com/

Pretty good aiming reference points, plus the 1in grid is nice for quick info.

[Sandbagger123]

I use white paper plates.Cheap and easy to see. just like shooting a 8" steel, but you can see the groups

[gose]

I tried shooting groups with my arms supported on my shooting bag to test accuracy of 9mm minor loads I'd been using in matches...and the result was awfully inconsistent. So I bought a rest.

Question - at what distance, using the rest, should be be shooting to best test the accuracy/point of impact of my loads? 25 yards? Multiple distances such as 10 AND 25 yards? Seems to me that the further out I get the more my human error is going to come into play...

Yes and no.

The absolute error will be bigger the further out you go, but relative to the distance it wont really make that much of a difference. Differences that might be hard to see/measure up close might also be more visible further out. Its also absolutely possible that a load that shoots very tight at 25y opens up considerably more at 50y than other loads that shoot equally well at 25y. The other way is possible, but much less likely.

When I was shooting PPC I tested everything at 25 and 50y to make sure it held up at both distances, for the most part using a Ransom Rest to remove the human factor.

However, with a stable shooting position and a large enough sample size (>=30), the impact of human error gets minimized and should be good enough to validate your groups.

Shooting groups at less than 25y is pretty much a waste of ammo IMHO.

[Red Ryder]

cpa5oh aka "Speed Demon":

After you zero your load to your gun, you may want to slow down a bit and focus on shooting the stages with all alphas, like me. But then you will also finished in the bottom end of the pack, like me

[GOF]

IMHO, a lot of bench rest accuracy testing depends upon the target you use. It needs to provide a very clear sight alignment/sight picture to a precise POA. The head box on a IDPA or USPSA target works well for me. The size, background, etc. lets me get a very consistent sight alignment/sight picture. The draw back is that shots off of it don't show.

The sight in target I now use at 25 yards (the distance I want to zero competition handguns) is a sheet of 8x11 white copy paper with a cut off head from a IDPA/USPSA target stapled over it. It's a crisp and clear sight picture. Put on a larger cardboard target back, it lets me see everything.

If your target doesn't give you a precise POA it will show in the groups you shoot.

I also just rest the gun in a normal freestyle grip lightly on top of a sandbag. This steadies the gun, and approximates the normal recoil I will get in a match shooting freestyle. And recoil is a factor in bullet placement because the gun will begin to recoil upwards while the round is still in the barrel, and the grip you use will determine where it recoils to. If the grip is inconsistent you will get vertical stringing that can skew accuracy tests.

It works for me, but maybe not for all.

Edited August 30, 2013 by GOF

[cpa5oh]

cpa5oh aka "Speed Demon":

After you zero your load to your gun, you may want to slow down a bit and focus on shooting the stages with all alphas, like me. But then you will also finished in the bottom end of the pack, like me

Ha! I WISH I was a speed demon...

[velo918]

Is 25 yards best sight in distance?

[pskys2]

If you want "Real" accuracy checks, use a Ransom Rest. Otherwise focus on 25 yds, I like to do it rollover prone, as that is the most accurate position I'll use in a match. You may have a problem with sand bags due to allowing the gun to recoil off of them. You still have to have proper grip, etc... you just use the sand bags to steady the wobble.

You can sight in 1" high at 15 yds, then move to 25 yds. Ilike to ultimately be sighted in 1-2" high at 25 yds, standing as I want to see the target above the sights. Then move to 50 yds and see where it hits. You can adjust a little at 50 yds and won't even see the difference at 15 yds. Whatever you do check the sight in at different ranges. And for USPSA you'll want to be most concerned with shot placement at 25 yds and under.

Remember that your POI will change between standing and prone/supported, for me it even changes between precision say a head shot or a plate vs an open target that I hammer 2 at. It has to do with how I muscle the gun around, some don't have that issue, some just don't realize it.

[velo918]

Thank you very much

[cpa5oh]

If you want "Real" accuracy checks, use a Ransom Rest. Otherwise focus on 25 yds, I like to do it rollover prone, as that is the most accurate position I'll use in a match. You may have a problem with sand bags due to allowing the gun to recoil off of them. You still have to have proper grip, etc... you just use the sand bags to steady the wobble.

This is interesting - so using the rest, you still grip the pistol the same as you normally do (i.e., don't just let it recoil as it wishes?) I was pretty much just setting frame/slide/muzzle into the "v" of the rest, lining it up, then pulling the trigger and allowing the gun to do whatever it wants as far as recoil - I don't even think I had my weak hand on the gun...I had no idea what I was doing...