wirehead
Lil-Rokslider
- Joined
- Nov 1, 2021
- Messages
- 244
Good Folks of R/S,
I’m baffled and bamboozled… bewildered and befogged…
I’ve been working on load development for a Win Model 70 in 7mm Remington mag - rifle has a 26” sportier barrel. The load I’m working with is IMR 4350 and 150 gr Accubonds with latest load being 62.6 gr of I 4350. Seating depth is 0.025” off lands. The issue: I’m seeing a systematic increase in velocity with each subsequent shot when doing 3 or 5 shot tests. The average increase is ~20 FPS and each shot is higher velocity than the previous. I monitor time between shots and always wait 3 minutes but typically 4 to 5. I may also be seeing a consistent point of impact shift subsequent shots compared to the cold bore but I believe there are not yet enough data to concluded such. Average group size is 0.75 to 0.9“ at 100 yd.
I have done previous load tests with 140 gr TTSX with H100v and 162 ELD-X with H4831 though ES was horrible with the H100v and I was not burning powder efficiently with the ELD-x and H4831 loads, respectively.
My next step is to run a 3 or 5 shot group letting barrel cool to cold bore each time… I need these data to confirm MV and POI so to properly conclude load development (before going to MT in 3 weeks ).
Thoughts greatly welcome!
I’m baffled and bamboozled… bewildered and befogged…
I’ve been working on load development for a Win Model 70 in 7mm Remington mag - rifle has a 26” sportier barrel. The load I’m working with is IMR 4350 and 150 gr Accubonds with latest load being 62.6 gr of I 4350. Seating depth is 0.025” off lands. The issue: I’m seeing a systematic increase in velocity with each subsequent shot when doing 3 or 5 shot tests. The average increase is ~20 FPS and each shot is higher velocity than the previous. I monitor time between shots and always wait 3 minutes but typically 4 to 5. I may also be seeing a consistent point of impact shift subsequent shots compared to the cold bore but I believe there are not yet enough data to concluded such. Average group size is 0.75 to 0.9“ at 100 yd.
I have done previous load tests with 140 gr TTSX with H100v and 162 ELD-X with H4831 though ES was horrible with the H100v and I was not burning powder efficiently with the ELD-x and H4831 loads, respectively.
My next step is to run a 3 or 5 shot group letting barrel cool to cold bore each time… I need these data to confirm MV and POI so to properly conclude load development (before going to MT in 3 weeks ).
Thoughts greatly welcome!