OK I've been developing (or trying to) a load on and off for my 243 BRNO 98 sporter for a few months now (from new). I've finally accepted I think there's something wrong. I can get it to group pretty well - like touching or half inch groups, but then it goes and throws a flyer. Not just one, and it's not just me. It's so regular I can't accept it's purely my error, and certainly not 2.5" every time.
This is certain to happen at least 1 in 3 times, no matter how many shots in the gorup. And the flyers always end up in the same spot 2.5" to the left - they themselves print a pretty good group! Basically I can't get a consistent group below 2"
What I've tried:
Powder charge - varying weights of N160 from 40 - 45.9 in .5gr increments
Varying seating depth - from 0.04" to 0.01" off the lands
Rests - proper sand bag rests front and rear. Also bipod
Chrono - crimped loads vary by about 20fps at 3000
Dry firing - when I do this the cross hairs basically don't move when I pull the tigger, all seems good
Bullet is 80gr remingington soft point
Barrel is a BRNO barrel, 22" with 1:10 twist
Moderator is P8 and I frequently check it for obstructions
I clean the barrel with Wipeout
Stock is walnut, free floated (double checked)
Scope is Vari-X II 4-12x40
Mounts are Millet Redfield style, and tight
Now I know I should try more bullets, and more powder. Well I guess that's the next step. But it seemed I could never get much of a difference when I varied the charge weight or seating depth, and surely I should be able to get a better group?
Should I be thinking about glass bedding it? Can a bad bullet match give symptoms this bad? I've only heard posotive things about N160 and how it increases everyone's accuracy so I'm thinking it's unlikely to be this too, but?
One more thing, I tried H1000 initially because Lee had some lying around he didn't want, and I decided on 46gr of it and hunted with it for a while. One time a shot a 1/2" group, but all other times it grouped 1.5" on a good day with the same old flyers. I could try this again I guess, but it's a badly matched powder I think for a slow twist 243. I'm sure I couldn't get a deer legal load out of it.
Can anyone help?