BSA,
You are right. I have tweaked brass many times primer pockets, deburred flash holes etc. but never enlarged the flash hole as it seems to be a complete waste of time. Where I think the OP is headed is down a rabbit hole that doesn’t lead to wonderland. Not once has he given a baseline in velocity.
Velocity = pressure just because all of a sudden a Mini14 and AR which are known to have generous chamber dimensions start chucking brass different doesn’t tell me a damn thing. I can say the same about my AR’s as I use a brass catcher. All go into a neat little pile in the bag. 😀 Did pressure go up or down? Sounds like down as it degassed his semi autos.
Whether it’s 5 shot or 10 shot groups the goal is the same shoot into one small hole. I usually run two 5 shot groups and chronograph with a 35P. I very rarely shoot the bullseye since I was taught to never shoot out your aiming point. When that’s gone you have to guess where in that hole to hold.
Also using wind as a reason for sh*t groups is no excuse. The OP sounds like he doesn’t know how to use wind flags, you shoot the conditions, waiting for a lull in winds to shoot a calm condition can be another exercise in futility.
Pick a single flag position that puts your sighters where you want them 10 ring for score or wherever on the scoring target for group and then shoot the same exact condition. A lot of times shooting full value is easier.
I applaud the OP’s efforts, but my opinion is he’s pissing in the wind.
Amen buddy. Great post.
