8 twist vs 7.7 twist on a 6-06 build?

[BD100]

Long time lurker, first time poster. Go easy on me.

I'm currently in the process of piecing together a 6mm-06 build. I was planning to use an 8 twist sporter contour and shoot primarily long, slick bullets, but nothing heavier than 105 or 107's. I have an 8 twist on order from Brux, which is 4-5 months out, but found a 7.7 twist that's available now.

My question is, is there much of difference between a 7.7 and an 8 twist? If so, what issues may I possible have with a 7.7 vs an 8 twist? Would over stabilization be a possible problem with the lighter bullets at the velocities a 6-06 would produce?

Thanks in advance for any input.

 

[jscandale]

In your case, or even a slower cartridge, an 8 twist will be just fine, but the 7.7 won't hurt at all. If you were experimenting with 115s, which is also a good option, you would need the rpm of a 7.5" for a slower cartridge. If I were you, I would go with the 7.7 if it is available to you just so you have the option of using 115s if the mood hits you some time. You will not need to worry about over stability even in a fast cartridge like a 6/06.

JS

 

[ShootDots]

What JS stated is exactly correct.. It could not have been said better..

 

[spclark]

Go with the 1:7.7. Just don't ever try to shoot Berger's 115 VLD which is worthless in anything slower than a 1:7 twist. Any of the 105 - 108 grain bullets'll shoot just fine in either & you have a little bit of an advantage with the DTAC 115 which will work in some 1:8's but not others.

Oh yeah, welcome to the forum!

 

[jscandale]

Steve,

I have never used a Berger 115 and have no experience with them, but at an estimated 3050-3100 fps at the muzzle, the 6mm/06 will produce about 285,000-290,000 rpm with a 7.7" twist. How much rpm does that bullet need? That's pretty close to the point where bullets come apart at around 320,000 rpm.

JS

 

[SDDasher]

Go with the 1:7.7. Just don't ever try to shoot Berger's 115 VLD which is worthless in anything slower than a 1:7 twist. Any of the 105 - 108 grain bullets'll shoot just fine in either & you have a little bit of an advantage with the DTAC 115 which will work in some 1:8's but not others.

Oh yeah, welcome to the forum!

Gosh, guess I have to throw my Dasher in the garbage because last spring I shot 115 Bergers in it with a 1x8 twist Krieger at 1K for a 195-5x and not the first one "came apart". I am currently working with a 1x7.7 Bartlein 5R in 6x47L for LR use of the DTACS or 115 Bergers......

 

[scope eye]

If you are going they 6mm-06 route, you might want to look into an AI version, I did and never looked back.

Dean

 

[spclark]

How much rpm does that bullet need? That's pretty close to the point where bullets come apart at around 320,000 rpm.

As with pretty much everything there will always be exceptions. Berger 'recommends' 1:7 or faster; I tried some in a 1:8 26" Schneider @ 2,900 fps & lost several on the way downrange. Same thing with a 1:7.5 PacNor @ - 2,850 fps then I shelved the rest in preference to the DTAC 115 which had just then appeared.

If they work for anybody in a 'slow' twist it'll get mentioned here I trust....

 

[BD100]

Good input. Thanks everyone. Sounds like a 7.7 will work fine for the intended purpose.

One last question....What is the lightest bullet I could get away with running. Thinking 80ish grains or so?

 

[scope eye]

Hi you can use the lightest bullet you want, just don't send them faster than to 3400FPS, that's 319,000 rpm or depending on how rough your your barrel is, it could be more but it could be a lot less, just keep sending them faster until they start vaporizing, then back off. I have a 12 twist AI and can shoot 105 Amax's if I send them 3500fps+

Dean

 

[spclark]

OK, I retract my statement.

It's apparent that several forum members have had success with Berger's 115 VLD in slower-than-recommended twist barrels.

Maybe I got a bad lot, maybe later on they switched to the thicker jackets several of their other products now use. After reading the positive reports I may be tempted to try them again in 2014... if they're for sale anywhere... in my 1:7.7 Bartlein 6XC.

In any event if your needs indicate using them might give you the results you seek, by all means give 'em a try! Follow up too with a report on your experiences.

 

[distinguished]

I would buy the 1-7.7 and keep the 1-8 for when the first one is shot out. I think barrel life will be short in a 6-06.