Thread: Load accuracy, 24" barrel to 18" suppressed.

Originally Posted by No.3

I think the options you have are the best of both worlds - shortening the 7x57 might make it useless with harmonics changes and lack of speed with the shortened barrel but you still have a handy .308 short rifle when needed.

If anything suppress the 7x57 so it takes the same can as the .308...

I find this with my hunting .308 - took it from 24" to 20" (didn't go shorter as I had an inkling I'd regret it). I am regretting going that short with it, as I'm finding that it just isn't generating the speed that the comparable but heavier barreled 20" version I have. The one I shortened is a 1-10", the heavy barrel is a 1-12" twist so you'd expect maybe a bit of difference but the 1-10" appears several hundred fps slower. Scratching head as to what to do now...

Greetings,
I did read somewhere that hammer forged barrels often have a slight choke going toward the muzzle. Sometimes this can result in significant loss of velocity when the barrel is shortened. You would expect around 100 fps loss going from 24 to 20 inches but it sounds that you have had more than this. Of course I can't find the source now. I have been working with a .308 lately with a 24 inch barrel that consistently produces more velocity for both factory and handloads than the data would suggest A different .308 with a 20 inch barrel gives around 160 less fps and is more in line with the data after allowing for barrel length.
GPM.