2 days after the last session, now with the 4th set of 3 rounds on most plates. Still using Corbon 155 Scenar ammo in the GA Precision Crusader 308. Chainsaw duty until mid-afternoon. Winds of 1-4 MPH from roughly 11 o'clock. Air Density Altitude has fortunately been within 600-700 feet for all 4 sessions, which minimized vertical impact differences among sessions. I warmed up with 4 dry fires this day, and I felt my technique was solid.

412 yards
Right hanging diamond. Now with 10 total rounds -- 3 from the start and 2 from the end of the box (rounds 19 and 20). Shots #1-3 and #19 were stacked on top of each other, just left of center. Shot #20 landed low, just above the 6 o'clock point. IMO shot #20 was likely a round with poor QC. With all 10 rounds the vertical variation is 6-1/8" and the horizontal is 8", which is definitely an increase from the previous session. If round #20 would have landed with this day's other 4 rounds, the vertical wouldn't have changed from the previous 3-3/4".

Left diamond. Now with 12 total rounds. Vertical remains at 3-3/4", but horizontal variation increased to 6-1/2".

410 yard square
Now with 12 rounds. Vertical increased slightly to 3-1/8" and horizontal increased a bit to 7-1/2".

Except for round #20 on the right diamond, I felt all impacts aligned with my expectations. I had very little movement in sights during the recoil process and I easily saw all my impacts. Shot #20 was about 5 inches lower and 1 inch right of what I expected.




527 yards
Square target, now with 14 rounds. Shots #10 and #11 landed on the left side, within the vertical range of the previous rounds. Shot #12 landed way low & right -- the impact in the corner. All 3 rounds broke during similar minimal winds, and I aimed just right of the left edge. This wonky impact was completely contrary to what my sight picture indicated.

Right diamond, now with 12 rounds. Vertical increased slightly to 5" and horizontal remains at 8-1/2".

Left diamond, now with 12 rounds. Vertical remains at 6-1/2" and horizontal remains at 8-1/4".




As I noted above, a shooter should know his typical error pattern. I feel fairly confident that the low impacts of rounds #12 and #20 were due to ammo issues, especially given the significant variations from that one bad box. The barrel's age might be factor -- it's now at 6800 rounds, which is high for a precision 308. Or maybe...I'm a dipshit and yanked a couple of shots in a manner which I don't normally do.

I believe I have at most 2 boxes left of this Corbon 155 ammo. I'm uncertain what's up next.