Help reading 2 targets

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minniehill2

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So I have had troubles working up a load and want your opinion.
I have 12 targets like the first one. Worked up through 6 grains of powder and all target have 4-6" of vertical stringing. POI between 4 and 6" high of center.





Today I changed 2 things....... I know, only change 1 thing at a time.

1 - I removed the muzzle brake from my gun
2 - I have been shooting off the bottom position of my bipod. I realised that that position is spring loaded (3/8" play) so I was locked in 1 position up.

The result......My POI lowered about 18"! and I have a circular group( I pulled the one out). 200 yard group.



I would have shot more but I need to load shells. The brake has a top holes to prevent rise. Do you think the spring loaded bottom position of the bipod would cause the vertical strings.
 
Is the first photo at 100 yards, or at 200 yards like the second photo?

In the first photo, I see four shots, forming a group 0.8" wide by about 2.7" high (assuming those are 1" squares). I don't see 4-6" of stringing. Do you mean that this group is 4-6" above your point of aim?


In your second photo, I see a larger 4-shot group (perhaps 2" wide by 4" high), that looks to be 10"-12" below what I would guess you were using as our point of aim?

Is your barrel free floated? If it is, your bipod and your shooting style (whether you load it or not, etc), are not going to make any observable difference to your point of impact.

Have a look at your muzzle brake. Is it possible it was on crooked, and the bullets might have been touching one of the baffles on the way out? Are they equally dirty, or is there a cleaner/less-fouled/scuffed/brighter spot in there?
 
nrbra,

First one is 200 yards also. My targets are 1" squares.
The vertical string target I posted has the least vert. So between 3-6. All are under 1" hor.
I have checked the brake multiple times, no sign of any strikes.

18" lower poi ? I will load/shot more tomorrow and bag the gun with and w/o the brake and see.
 
An 18" change of POI at 200 yards is nuts. The good news is, whatever caused it is something major, not subtle.

At this point I'd say that the suspicion is on your brake. Shoot some groups without it. If the rifle shoots well without the brake, then that means you have confirmed proper operation from all parts of the system (barrel, ammo, stock & bedding, scope mounts and bases, scope internals, shooter, etc). You have an end-to-end known good base case.

If you're interested in being able to use your brake, install it after you've got a good baseline (shooting round groups smaller than 1MOA, or even better, closer to 1/2MOA, on a regular basis). If there is *some* shift in POI with the brake put on, that's unfortunate but acceptable (by "some" shift, I mean a few MOA). If the group with the brake on opens up, then there is definitely something wrong with either the brake itself or how it is installed (a brake should *not* cause any increase in your group size - if it does, something is wrong and needs fixing).
 
So I made it out tonight for a couple more shots. I re-installed the brake and fired 4 rounds. No point in posting the picture as this happened. Needless to say I am a little pissy with the gunsmith that installed it.



This was the group without the brake @ 200 yards


At least I know what the problem is now.
 
Problem solved and I have a happy shoulder!
When the smith turned the shoulder into my barrel, he went .002 too far in. The brake was timed at 1 o'clock so he used a set screw in the bottom of the brake to hold straight up. The screw was tilting the brake very slightly. I cut up a shim so the two shoulders would lock up. Voilà.... 1.1 MOA on a starting load.
 
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