I’d change brass or bullet, change nothing else pick one of those two, then go from there. Obviously better brass won’t hurt anything. Measure H20 capacity though, some brass like my M118 brass is lower than usual capacity, you might be higher in pressure than you expect at that powder charge.
Also in my experience the 169gr SMK outperforms the 168, but your dispersion being what it is, I don’t think is due to the projectile… your rifle either HATES the SMK projectile which I doubt, or something else is up.
How often do you practice?
What rifle?
What’s your rate of fire like?
The bullets in my post are 168 ELDMs, I did shoot some factory ammo with 168 SMKs (@2430fps) the same day at 600yards but the ES was 80fps and they sucked in the wind.
My barrel is a 1:12 twist and at 2500fps the 169 SMK isn't going to be particularly stable.
If I change bullets I'll likely drop down to a 155gr.
Rifle is a AI AT, was a fairly fast rate of fire not PRS match quick but I wasn't pausing between shots.
I wasn't seeing the groups open up as the string went on, but I could look out for that next time.
The rifle is pretty new to me, and I haven't shot much centrefire lately (a lot of rimfire though) but my recoil management was pretty good, the trigger pulls felt good. My shooting was no worse at 600 than it was at 300.
I'll try to bring down the ES from the current load (different brass and/or different sizing dies).
I should weigh the S&B brass and see if is as inconsistent as I'm making it out to be.
