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Please post your findings with the 7-08 I have a couple fast twisted 7's they would be fun in
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No reason not to go 8. See for yourself. And 8 twist at sea level...
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So got a box of these things today. In my rig they hit the lands at 3.56 OAL. With what I think will be max loads of Retumbo, I have a very full but not compressed case. Looking forward to shooting them hopefully next week and will post speeds for my 25" 7mm RM.
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Definitely no reason not to go 8 or 8.5, except if you can't get one and the 9 twist is in your hand. Hello Rick, Thank you for contacting Berger Bullets. You should be okay with the use of the 1:9” twist barrel. Our tests have indicated that you can go as slow as a 1:9.3” to maintain marginal stability with this bullet and that is the reason for our confidence with this bullet for you. Please do not hesitate to get back with any of us with the Berger Tech. Team if we can be of further assistance. Kind Regards, Bob Blaine Technical Specialist Berger Bullets Technical Support Team [email protected]
The people wringing their hands over Trump's rhetoric don't know what time it is in America.
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Quick update. The 8.5 twist Rock at 5200 foot altitude didn't seem to have trouble stabilizing the 195s at all. Velocity in a 7mm RM with 25" barrel ranged from 2800 to 2890 going up from 66 grains of Retumbo to 69 grains.
Did not see pressure signs but thinking 69 has to be getting pretty close to max. Will work on seating depth a bit to see if I can tighten groups up a bit more but happy to see the velocity where it was.
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Well I won't argue with you there! Kimber 7-08, 9" twist... These should work!
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Any idea of velocity with the 7mm-08? Anxious to get back out and shoot these again.
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Yeah, that load was giving 2412fps in the Kimber. I could step on the gas a bit more and get 2500+fps out of it, but this was just an experiment to see what they'd do in the 9" twist barrel going fairly slow. That rifle will continue to be fed a steady diet of 162AM's... Dug out this 195 from a gravel pit behind the log... Dug this 162 out a week ago from a meat bull moose. Busted the onside humerus and was found under the offside hide. The second shot went through ribs and heart/lungs and exited. Slight quartering shots at 150ish yards. No reason not to stick with this bullet from the 7-08...
Last edited by Jordan Smith; 10/19/15.
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4 shots at 600, 3 of them in 7/8" Went out yesterday to verify drops as far as the scope had travel. I had verified drops to 800 during development and Ballistic AE showed velocity at 2965 fps when entering all pertinent info. Shot a group over the chrono. Average was 2965 with an SD of 3 Used that data to to make multiple impacts at 1580 yards in 13-15 mph cross wind. 2 mils The 9 twist causes no degradation of BC whatsoever
The people wringing their hands over Trump's rhetoric don't know what time it is in America.
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Jordan, let's see what the 195 will do outta' your Montana 7 WSM.... And some details on what that new tube and Holland lug are going to be used for....
Tanner
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Tanner, Long time, no talk! Looks like Alaska was a fun adventure, yet again. I've got 10 loaded up for the Montana 7WSM, and I'll take it out to see what's up as soon as I'm done sheep hunting for the season. I'm hoping to see 2800-2900fps. The new pipe will be going on another 7WSM build, this one will be on a 700 LA with PTG 1-piece bolt. I'm thinking 25" finish and something like a Greybull stock or a Mickey GS or Manners EH1 should balance it out nicely. It'll be throated for the 195, so I'm hoping for good things from that bullet. Here's what my RAR 7-08 did with its 9.5" twist. BTW, these groups (from the Kimber and RAR) were shot while I was in moose camp at 2500 feet ASL in 40 deg temps. Ignore the top right 2 shots and bottom left 4 shots that were from a bud's rifle. You can see evidence of some pretty unstable bullets...
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Went out yesterday to verify drops as far as the scope had travel. I had verified drops to 800 during development and Ballistic AE showed velocity at 2965 fps when entering all pertinent info.
Shot a group over the chrono. Average was 2965 with an SD of 3
Used that data to to make multiple impacts at 1580 yards in 13-15 mph cross wind. 2 mils
The 9 twist causes no degradation of BC whatsoever
Rick, Glad they are shooting so nicely for you! Are you using the published G7 BC from Berger? I'm thinking either you're high enough and in thin enough air that the 9" twist isn't causing your SG's to come below 1.5, or else you're getting published BC's even with an SG of under 1.5, and you'd get even slightly better BC values with a faster twist. Interesting...
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Yep. Just took the BC figure right from the box since AE hasn't updated with Litz's figures. Took a length measurement with calipers for the Spin Drift calculations.
I'm at 5000 ft of altitude and I'm sure that helps. Even though, Berger states right on the box that their testing showed the bullet will remain stable with a twist rate as slow as 9.3 and I'm sure that means at sea level.
The 7mm-'08 probably can't shoot it fast enough to stabilize.
The people wringing their hands over Trump's rhetoric don't know what time it is in America.
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Just noticed something interesting- on the box in the OP's picture, the minimum twist rate specified is 9.2" or faster, if you look at the box further down in my pic, the minimum twist spec'd is 9" or faster. Got a pic of the top of one of your boxes? Sounds like they changed the minimum recommended twist at some point. Which batch did you get in on, the first lot, or the second?
I do most of my target shooting at 4000-5300 ft ASL, but in this case I was at moose camp at 2500. Interesting that with the exact same 7-08 load the RAR was keyholing and the Kimber was punching nice clean, round holes and grouping nicely (for a factory tube on a 6lbs scoped rifle). Seems like the 9" twist on the Kimber was sufficient to maintain stability, but the 9.5" twist on the RAR wasn't.
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Mine says 9 or faster. Realize that just because your barrel is supposed to be a certain twist doesn't mean that it is that twist rate exactly. Do the cleaning rod test and measure accurately
If you reread the email straight from Berger that I posted, it states that they have tested the 195 in barrels as slow as 1-9.3" and the bullet maintained stability
The people wringing their hands over Trump's rhetoric don't know what time it is in America.
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Campfire 'Bwana
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Went out yesterday to verify drops as far as the scope had travel. I had verified drops to 800 during development and Ballistic AE showed velocity at 2965 fps when entering all pertinent info.
Shot a group over the chrono. Average was 2965 with an SD of 3
What a beast! Rick curious what is the velocity of that load at 1500 yards?
The 280 Remington is overbore.
The 7 Rem Mag is over bore.
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- Greg
Success is found at the intersection of planning, hard work, and stubbornness.
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Campfire 'Bwana
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That seems pretty impressive!
The 280 Remington is overbore.
The 7 Rem Mag is over bore.
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Not Rick, but my avg hunting elevation is 10,000 feet. That bullet started at 2900 is still doing 1750 at 1500 yards. At 1000 yards it has 2100 fps and 1900 foot pounds of energy.
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Mine says 9 or faster. Realize that just because your barrel is supposed to be a certain twist doesn't mean that it is that twist rate exactly. Do the cleaning rod test and measure accurately
If you reread the email straight from Berger that I posted, it states that they have tested the 195 in barrels as slow as 1-9.3" and the bullet maintained stability Confirming a barrel's actual twist rate is a given before a bullet ever passes down the bore, but Berger's numbers are based on actual twist rates. In the email it says that you can go as slow as 9.3" to maintain MARGINAL stability. According to Bryan Litz, a bullet in the marginal stability range with an SG between 1.0 and 1.5 will lose about 3% of its BC value for every 0.1 SG under 1.5. Maximum BC is realized for anything over 1.5. Hence the reason for my wondering if you'd see higher than advertised BC values if you had a faster twist rate, if you are indeed under 1.5 in SG, of course...
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