If he did not have the correct data in the calculator he would not be making hits at different distances. Calculations are just that. Validation is law. Back to the OPs question. If I were you I would try a different bullet.
max 2775 fps .why not more?
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PowellSixO
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According to my Chronograph, I'm at 3025-3050 fps. According to the G Seven Ballistics Program, I'm only getting 2965 fps. With the corrected fps calculation, my drops are perfect out to 600 yards (the furthest I've shot). I'm blaming my high reading on my chronograph. According to the reloading information I'm using, my corrected fps of 2965 fps is pretty much right on the money. According to the load information I have, 69.5 gr of H1000 and the 168 gr VLD (which is the published max) with a 26" barrel, they list 2987 fps. So I'm right where I should be, plus a few fps. I'm not sure why you're getting such low fps. That's a head scratcher for sure.
I do show 70.7 gr of Ramshot gives 3017 fps, and also 65.3 gr of IMR-7828ssc gives 3002 fps. You might want to give them a try. But I wouldn't be too worried about not being over 3000 fps. It's just a number. If your load is accurate, that's what really matters.
What are your actual drops for lets say 500, 600, and 700 yards?
PowellSixO
Well-Known Member
If I were you I would move to 180 Bergers with Retumbo. You would need a 9 twist and the correct throat so I am not sure how they would do in your 9.25. I have no explanation for the slow speeds but I will say that case is more efficient with a larger bullet and slower powder. My WSM shoots 180s at 2980 with 66 grains H4831SC in a long action with a long throat. I ran some numbers and it seems you 168s are seated pretty close to the optimal depth. The 180s would be a little more into the case than I would like. You could also try some 162s.
Lefty7mmstw
Well-Known Member
Switch to a double base powder.
h4831 and h1000 are both single base and yield about the same energy per grain and it is less than a similar speed double base powder. I would try rl26 if I were you... I have burned more rl22 and rl25 in big 7''mms than anything else, but if I were to start today it would be rl26. About the only other powder I will burn in a big 7mm is retumbo- my 7rum likes that powder with 175-180's ( when I finish torching that pipe I'll try to get the next barrel on rl powder though)... Rl 26 produces very good velocity in 7mm and is pretty temp stable, not to mention it has de-coppering agent.
h4831 and h1000 are both single base and yield about the same energy per grain and it is less than a similar speed double base powder. I would try rl26 if I were you... I have burned more rl22 and rl25 in big 7''mms than anything else, but if I were to start today it would be rl26. About the only other powder I will burn in a big 7mm is retumbo- my 7rum likes that powder with 175-180's ( when I finish torching that pipe I'll try to get the next barrel on rl powder though)... Rl 26 produces very good velocity in 7mm and is pretty temp stable, not to mention it has de-coppering agent.
