6.5CM Twist Rate & Barrel Length

[Cardboard Assassin]

I'm pretty sure its time to swap my 6.5CM barrel (round count is up there and accuracy has dropped off a cliff)

The original barrel is a 1:8 twist and I have had good luck with various 140gr bullets but I have some heavier bullets so was wondering if I should go for a 1:7.5 twist.

I ran the numbers on the Berger calculator and it looked like the 1:7.5 would work best for the range of bullets I have (139 gr Lapuas / 140gr ELD-Ms / 144 gr Lapuas / 150gr Sierras).

With this in mind is there any reason not to go with the 1:7.5 twist? Will the accuracy of the lighter 139gr / 140gr bullets be affected by the switch from 1:8 to 1:7.5?

What is preferred barrel length for 6.5CM? I have a 24" right now which has served me well but its a slow barrel for sure (it ran best at 2650 FPS), from what I have read it seems 26" seems like a popular option and should take me to the ~2700 FPS which is more typical for 6.5CM.

Thoughts?

 

[Whiskey_Tango6.5]

I'm running 156 EOL's at 2,800 out of a 1:7.5, 26" barrel.

 

[huntnh]

I’m running a 26inch with 140g eldms at 2750 could push it harder but I don’t see a need

 

[BoilerUP]

I’ve never had issue with a 18” 1:8 running 147s around 2525fps.

 

[308Gunner]

I just ordered a 8.5-7.5 Bartlein, I have had 8 twist and also 7 twist barrels. If you are going to run the heavy bullets go faster if not an 8 will be fine.

 

[Cardboard Assassin]

I just ordered a 8.5-7.5 Bartlein, I have had 8 twist and also 7 twist barrels. If you are going to run the heavy bullets go faster if not an 8 will be fine.

Sounds like 1:7.5 will fit the bill nicely......