18" barrel varmint rifle?

[Northern]

I am building two varmint rifles.. a 222 and 6BR.

I am planning on 18" barrels, as I will have a suppressor on 99.9% of the time. Its 6" long.

I was wondering what speeds I should expect with
40-50 grain in 222
65-75 grain in 6BR?

I have S&B 10x42 scopes for both, Klassik, not PMII.. so just point and shoot. 300 yards MAX.

[orkan]

I have quite a few 16" to 20" rifles.

This thread of mine might interest you:
https://forums.gunhive.com/topic/255...-light-bullets

[NeilA.]

I have a few 19 inchers threaded for a suppressor.

Whatever velocity I sacrifice is worth it to me, rather than dealing with an xxlong rifle.

[TinMan]

For what it is worth, about ten years ago I got curious about claims about velocity loss with barrel length. So I found every 223 Rem firearm we could find among our group of friends, regardless of action type, AR, bolt, T/C, etc.. Barrel lengths ran from 8" to 26", and all used the same 55gr FMJ commercial ammo. The end result was 29 fps per inch of barrel length.

[orkan]

The more overbore a cartridge is, the more FPS is lost per inch, the shorter the barrel gets. Longer barrel lengths tend to be less FPS loss, until you get below a certain threshold of powder burn, then FPS loss increases with each inch removed.