6.5 mm twist rate

[Slamfire]

If I am interested in building a long range bolt rifle with a 6.5 mm barrel, and it is most likely to be 6.5-08 or 6.5-55 (because of the number of cases I have), what twist rate is appropriate for the heavier Sierra match bullets?

 

[Ramsgate]

The CG-63 competition rifles were intended for 300 meter competition and their 6.5x55 barrels had a 1:8.6 twist and I assume they had 140 grain bullets in mind. The 6.5x55 is a remarkable cartridge ... it's one of those very few that seem to be automatically accurate but if you have the brass, you will have already formed your own conclusions. I have shot a great number of 7mm-08 loads which must be similar to the 6.5mm-08 and they certainly were not so forgiving.

 

[~z]

for 140 & 142gn bullets look for a 8" twist. A small tip for you, consider building on a long action. To take advantage of powder capacity you will want to seat your bullets way out (and 140gn Bergers are LONG bullets) short action will not allow them to fit the magazine. Good luck! I'm building one myself, 6.5x284. Parts are arriving slowly.
~z

 

[Howard Roark]

I had my .260 reamer cut with a short throat. That way I can chase the throat farther for longer barrel life. I only shoot the rifle in NRA prone matches where we single load.

 

[Hoser]

All my 6.5s use 8 twist Lilja 3 groove barrels except for one Schneider Poly 8 twist.

No problem with any bullet weight from 107 to 155. Mainly 139 and 142s though.

 

[shooterer]

Palma rifle forum

Go here for answers to all your questions my son.

http://www.usrifleteams.com/lrforum/index.php?&

You may need to sign up.

Jim

 

[Dr. Tad Hussein Winslow]

My limited understanding is that 1 in 7.5 is best for super-long bullets like an all-copper 140 or some such, but 1 in 8 will work fine for pretty much anything else, including some long ones.

 

[Slamfire]

Buggers! Brownell's only has a 1:9 shilen heavy barrel blank.

Guess I will have to look around for a 1:8 or tighter.

Thanks to all.

 

[pdd614]

I went with an 8 twist shilen because my smith had one, but put in an order for a 8.5 twist bartlein. Should be perfect for anything between 120-140 grains.

 

[Hoser]

Should be perfect for anything between 120-140 grains.

Thats a pretty big (and expensive) roll of the dice. I would rather over stabilize a bullet that have it not be stable...

 

[Howard Roark]

I've shot many 199 and 200's with my .260 at 600 and 1K with 142gr SMK and 140 Bergers. 1-8 Hart barrel. Everyone I know with a 6.5mm shoots a 1-8.

 

[pdd614]

Hoser, I guess only time and load development will tell if i'm correct about the 8.5 twist.

 

[USSR]

I went with an 8 twist shilen because my smith had one, but put in an order for a 8.5 twist bartlein. Should be perfect for anything between 120-140 grains.

IMHO, the 8.5" twist is ideal for the 139-142gr 6.5mm bullets. That's what my 6.5x55 chambered Obermeyer is.

Don

 

[pdd614]

i had a feeling the 8.5 twist would be perfect for my little lapua, but i can't complain how the 8 twist is shooting so far. these 6.5's are just too nice.

http://www.thehighroad.org/showthread.php?t=459273

can't wait until my 130 jlk's get here.