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Joined: Mar 2007
Posts: 938
Campfire Regular
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OP
Campfire Regular
Joined: Mar 2007
Posts: 938 |
I have a Cooper in the 6.5 PRC that someone wants more than I do. I am going to regret this, as it will shoot 124 HH in the .2's. I do not want to be without a 6.5 PRC and I was looking at the Proof Research Tundra, and G. A. Precision rifles. Both of those firms are twisting their barrels at 1:7.5 twist vice Coopers 1:8 twist. What is this giving me that the 1 in 8 twist doesn't?
I know this should go down in the reloader forum, but I figure most reading here are reloaders and can tell me if the 1:7/5 will stabilize the 124 Hammer Hunter bullet.
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Joined: Aug 2006
Posts: 861
Campfire Regular
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Campfire Regular
Joined: Aug 2006
Posts: 861 |
It’s a faster twist than your 8 twist. It will stabilize anything the 8 does and likely a bit more.
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Joined: Apr 2011
Posts: 15,303
Campfire Ranger
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Campfire Ranger
Joined: Apr 2011
Posts: 15,303 |
I wouldn’t worry. If they shoot in the 8, they’ll work just as well in the 7.5. Maybe better terminally as well.
Semper Fi
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Joined: Jul 2008
Posts: 192
Campfire Member
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Campfire Member
Joined: Jul 2008
Posts: 192 |
Sierra recommended 7.5" for their 156gr Matchking...you like copper projectiles, so when they make a copper heavier than 130gr, you might want 7.5" twist.
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Joined: Jul 2001
Posts: 60,123
Campfire Kahuna
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Campfire Kahuna
Joined: Jul 2001
Posts: 60,123 |
There's also a considerable difference when shooting at higher elevations. A general rule is that every 5000 feet in altitude requires 1" less twist for bullets to stabilize.
20+ years ago I had a 6.5-06 with a 1-9 twist, because a barrel company offered to build me one--and that was the fastest 6.5 twist they offered at the time. Generally I hunt locally at around 6000 feet above sea level, and the rifle grouped 140-grain Berger VLDs into 3" for 3-shot groups at 600 yards. Obviously they stabilized very well.
The Berger bullets stabilization formula (and some others) can provide a good comparison between various altitudes, and other programs work well too.
“Montana seems to me to be what a small boy would think Texas is like from hearing Texans.” John Steinbeck
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