I have not shot them on game as of yet. I will this fall. I've read some reports they perform amazing. I haven't seen any negatives yet. But they are freaking lasers
6mm Creedmoor barrel twist?
- Thread starter TAZMAN
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Hugnot
Well-Known Member
I tend to believe that Sg values around 1.6 and under 2.0 are common to optimum or winning performances in LR BR shooting.
I have shot some bullets that have had Sg values under 1.5 that have performed well.
The JBM site is a good source for indications of bullet stability, their Sg calculations match my spread sheet values that I derived & copied from Miller's formula. I have found some of the JBM bullet lengths incorrect, best to measure bullets. The Berger site has a bullet stability calculator that advises that under 1.5 - "Your bullet stability is marginal. You may shoot good groups under these conditions, but the BC of the bullet will not be optimized." Berger uses the Miller process & probably uses bullet wizards.
For my use as a casual shooter, I measure bullet lengths, make note of temperature & pressure, measure velocity, get a Sg value, then shoot. I have selected 8 twist for my use, thinking it would perform well for the less trendy & lighter, low form factor, 95 grain bullets that can be driven over 3,100 fps giving flatter trajectories over my common distances, like under 800 yards. I got some 1.5 inch or so groups at 300 yards using the 95 grain Berger (Sg 1.7 @ 35 F) from a 8 twist. I like the cheap 105 grain Barnes Match Burner for my 8 twist barrel, Sg values 1.6 - 1.7.
The commonly used, old type, untrendy, low BC, inadequate long range, and cheap 87 VMax shot at just under 3,500 fps and has performed well on small targets up to 800 yards from a 10 twist 6mm AI. My 6mm-06, 8 twist, blew the 87 Vmax's up at over 3,500 fps, gray smoke. I think a 8 twist 6CM producing a Sg of 2.6 with the 87 Vmax's would be a bad choice, I get 2-3 inch groups at 3,250 fps. I only shoot 95 to 105's from my 8 twist 6mm CM.
I have shot some bullets that have had Sg values under 1.5 that have performed well.
The JBM site is a good source for indications of bullet stability, their Sg calculations match my spread sheet values that I derived & copied from Miller's formula. I have found some of the JBM bullet lengths incorrect, best to measure bullets. The Berger site has a bullet stability calculator that advises that under 1.5 - "Your bullet stability is marginal. You may shoot good groups under these conditions, but the BC of the bullet will not be optimized." Berger uses the Miller process & probably uses bullet wizards.
For my use as a casual shooter, I measure bullet lengths, make note of temperature & pressure, measure velocity, get a Sg value, then shoot. I have selected 8 twist for my use, thinking it would perform well for the less trendy & lighter, low form factor, 95 grain bullets that can be driven over 3,100 fps giving flatter trajectories over my common distances, like under 800 yards. I got some 1.5 inch or so groups at 300 yards using the 95 grain Berger (Sg 1.7 @ 35 F) from a 8 twist. I like the cheap 105 grain Barnes Match Burner for my 8 twist barrel, Sg values 1.6 - 1.7.
The commonly used, old type, untrendy, low BC, inadequate long range, and cheap 87 VMax shot at just under 3,500 fps and has performed well on small targets up to 800 yards from a 10 twist 6mm AI. My 6mm-06, 8 twist, blew the 87 Vmax's up at over 3,500 fps, gray smoke. I think a 8 twist 6CM producing a Sg of 2.6 with the 87 Vmax's would be a bad choice, I get 2-3 inch groups at 3,250 fps. I only shoot 95 to 105's from my 8 twist 6mm CM.
GoosePilot
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- Feb 3, 2018
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I did a very quick load development for my 1:8 24" proof cf with 75 vmax at just under 3600 fps last fall before a local shoot. Shot great to 500yd. Then used the rest during a coyote calling contest. 30yd to 324yd kills. I'm at 3000ft msl
