barrel twist for a 180gr 7mm berger?

lip_curl · Dec 22, 2010

berger recommends a 1:9 twist to launch this bad boy. i currently have 1:9.5 does anyone have real world experience shooting the bullet in both barrels? is the accuracy lost due to shooting in a 9.5 significant? i asked berger and they only responded with "we recommend 1:9"
thanks..

lip_curl · Dec 22, 2010

doh! stupid emoticons..
trying to decide if i need a 1 in 9 twist or if 1 in 9 1/2 will give me the same results...

completesportsman · Dec 22, 2010

If you're buying a new barrel I would get the 1-9. If you already have a 1-9.5 then I'd try it.

Meander · Feb 7, 2011

I shoot a 180 grain Berger VLD from my factory Remington 700 Sendero chambered for 7mm Ultra Mag. It has a 1 in 9.5 twist. I have installed an extended magazine box so I can seat the bullets to a longer overall cartridge length. It flies through the Chrony at 3250 fps fifteen feet away from the muzzle and holds sub moa accuracy from a bench from between 200 and 800 yards. The best I've been able to do is hit a 4" orange target circle 3 out of 5 times at 800 yards. The other two were just outside the circle by an inch and 2.5 inches respectively. The environmental conditions were an elavation of 5000 ft and 50 degrees. I'm pretty sure the higher elavation and velocity has alot to do with allowing a 1 in 9.5 twist to stablize the heavier bullet. I doubt it would shoot at an elavation of 2000 ft. If I were going to build a rifle around that bullet I would go with a 1 in 8.5 twist.

lip_curl · Feb 7, 2011

thanks...
i was able to dig up some tech papers on barrel twist and they told me the same thing, at sea level, i might have problems, but should be barely able to get away w/ a 9 1/2 twist. If i do rebarrel, i will go w/ a faster twist. did you try the 168s? how did they perform vs the 180s?

beavis14 · Feb 8, 2011

a 180 grn .284 bullet ? sheez that sucker will be 2" long. whats the m.v. expected 2400 fps ?

lip_curl · Feb 8, 2011

3125 coming out of 7RUM.

for a sub 3" group at 1000yds..it can be as long as it wants to be.

http://www.6mmbr.com/gunweek071.html

REDDOG · Feb 8, 2011

I could stabilize them with a 9.5"@ 5000 feet out of my 7wby..A 280 with the same twist didnt fair too well.

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