8 Twist and 90's

[yukonal]

Will an 8 twist stabilize 90 grain Begrers in a .223?

 

[MarkS]

NO Most guys go with 7 or 6.5 tw.

Mark Schronce

 

[FroggyOne2]

Only time you need a 6.5 twist is for the 90 gr Sierra

 

[Laurie]

Definitely not. I've had excellent results with 1-7" with the 90gn Berger LRBT and VLD, not to metion the JLK VLD. A 26-inch 1-7.5 4-groove Bartlein works very nicely with the Berger LRBT at modest MVs (~2,650 fps), but that appears to be as slow as you can go. 1-7.7 works well in some conditions, but not others. Twist rates around 1-7" seem to be the way to go with most of these bullets. Bob Pitcairn in Canada is doing very well with the Berger VLD using 1-7.2 or 1-7.25".

Adequate (= long) freebore is as important as twist in making this combination work.

 

[rcw3]

Only time you need a 6.5 twist is for the 90 gr Sierra

Honestly Sierra's twist recommendation there is excessive. A 7" twist is fine for those bullets.

 

[FroggyOne2]

Robert,

I fully understand that, I didn't really complete what I meant too say, due to the short bbl of a Service Rifle the 6.5 twist is more appropriate. The longer bearing surface and the lower velocities from a 20" bbl.

Laurie,

With Berger bullets, yes you are correct. I use a 7.2 twist exclusively. But comparing a Berger 90VLD to a Sierra 90 is almost like apples and oranges. They are deff two different animals.

 

[Laurie]

With Berger bullets, yes you are correct. I use a 7.2 twist exclusively. But comparing a Berger 90VLD to a Sierra 90 is almost like apples and oranges. They are deff two different animals.

Point taken, although as it's a shorter bullet for its weight than the Berger / JLK models, it should maybe just work in a 1-8" even at service rifle MVs. I have a straight-pull AR-15 (ie manually operated as we're not allowed dangerous guns like semi-autos in the UK) that had a 24-inch 1-8" LIlja heavy match tube in its .223 Rem days.

Given the lack of gas assistance we can only load these animals' fodder up so hard if we want to open the bolt without a mallet, so it ran 80s at the sort of speeds you guys get from 20-inch barrel SR competition rifles. I tried the 90gn SMK after it came out and it did group at 100 with whatever velocities I could get from a case-full of Viht N550 - well, it grouped sort-of, like one to two inches, and oval holes throughout. That was on a range around 900 ft ASL and in ~20-deg C temperatures, so I concluded even short 90s and 1-8" don't get on.

1-7.5 instead of Sierra's 1-6.5 should suit this bullet well. I have a few left over from the abortive experiment, so I maybe ought to try them in my 1-7.5 Savage / Bartlein one day to see how they do.

 

[FroggyOne2]

Laurie,

It will be intersting to see what you come up with with the Savage.