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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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
Just a quick update with load data. Been working on the load for this new rifle and was not seeing the groups I wanted with H4350 and the 105 Berger. I have 500 of the Bergers and want to use them. An older buddy of mine use to do F class and build rifles and he wanted to do some testing with it. He has a gamete of different powders that I don't have.
He tested several powders and RL19 with the 105 Berger seems to be the winner but slow. The barrel has 56 rounds through it now. This is the 1-7 twist barrel discussed earlier. I have some 115 Bergers that I may try next. I have not tried RL26 in it yet. I have 36 pounds of it, but it is used in my 6.5 Creedmoor rifles.
He tested several powders and RL19 with the 105 Berger seems to be the winner but slow. The barrel has 56 rounds through it now. This is the 1-7 twist barrel discussed earlier. I have some 115 Bergers that I may try next. I have not tried RL26 in it yet. I have 36 pounds of it, but it is used in my 6.5 Creedmoor rifles.
fseaman
Well-Known Member
It's been a bit but I remember really liking R19.
Did he load them or did you? I ask because if he loaded them, you would have to duplicate all aspects. COAL, neck, bump. I'm sure you know.
.186 and 0 spread is hard to beat. Sometimes chasing more velocity is a losing proposition. I'm sure you know.
Berger's own loads are only a tiny bit faster than that 2911.
Are you match shooting with it or hunting?
I had good luck with the 108 ELDm and RL-26 in my 7 twist. I'd definitely give it a go with the 105s and 115s if you have plenty of it.
He did the loading with my dies and bullets. We use the same rock chucker old time press so duplicating the load shouldn't be an issue.
I tried the 108ELDM and had a couple blow up at about 3140fps. They didn't group really well but if I slowed them down, they may work ok.
I only built this gun for fun because I had the Savage action, stock and bottom metal from a standard set up. I built two identical rifles on Savage actions. the first one was the 308 which I put in here and this one is literally identical except caliber. This one has been a pain. Had to machine some things on the action to make it feed like a custom. Fortunately, the 308 seemed to have a little better tolerance.
I tried the 108ELDM and had a couple blow up at about 3140fps. They didn't group really well but if I slowed them down, they may work ok.
I only built this gun for fun because I had the Savage action, stock and bottom metal from a standard set up. I built two identical rifles on Savage actions. the first one was the 308 which I put in here and this one is literally identical except caliber. This one has been a pain. Had to machine some things on the action to make it feed like a custom. Fortunately, the 308 seemed to have a little better tolerance.
