Barrel twist rate?
 

Howdy,
I intend to shoot 220 and 240 SMK bullets sub sonic only. What is the better twist for the barrel.

1 - 7 , 1 -7.5 , or 1 - 8
Thank you.

..one/eight

Thank you Spook

If i can borrow the thread, I´m building a whisper and would like to know how lighter bullets perform in say a 1:8 twist? How heavy bullets can i shoot in 1:8?

The question you ask is more complex than it might appear. Lighter bullets may shoot well if they don't have problems with blowby or excessive jump before reaching the lands. The answer is to try various bullets and loads to see how they work. I doubt anyone can tell you what will and won't work in your chamber.
If twist is the only consideration, lighter bullets will generally shoot more accurately than heavier bullets for any twist at short range. Heavy low drag bullets get their accuracy at long range from having less wind deflection and less velocity dispersion since they will (at some distance) have a shorter time of flight.

Bullet shape, length, and material all matter in determining stability as does weight. You could shoot 300 grain tungsten core bullets if you could find some. You could shoot 300 grain cast lead short ogive bullets in an 8" twist if you don't mind the fouling. It also depends on the atmospheric conditions where you shoot. In "normal" conditions you should be able to shoot 240 grain Sierra matchkings. You probably cannot shoot 220 grain Lost River solids. Though they're lighter they are longer and less stable than the 240SMK. I doubt you can shoot the 240 SMKs in sub-zero arctic conditions as the air is too dense. One person here reported being able to shoot 240SMKs with good accuracy from a 10" twist barrel, but he was shooting at 10000 feet elevation with low air density.

Will most likely only shoot heavy bullets but you never know. Guess i´ll have to try, thank´s.

I have shot everything from 110 Hornadys to 240 Sierras through several 1:8 barrels ... all without issue...

Sound´s good:smile: