Short Barrel .308"

[Jonny]

We have a .308" that has a 28", 1-14" twist, barrel on it and we are considering cutting this down to around 18"-20" and fitting a suppressor and using it for sub 600m work. I'm aware of the trade-offs in terms of velocity but I'm curious as to what people think about this twist stabilizing the bullet in such a short barrel. Does a short barrel need a faster twist or will these bullets still stabilize adequately? I've done a bit of trawling around but most production .308"s with short barrels seem to have a 1-10" in them.

 

[stubbicatt]

I know *generally* the shorter barrel requires a faster twist. The example I am aware of is the little AK74 with the 10" barrel has a faster twist than the standard infantry rifle in order to stabilize the 5.45 round.

As to how fast the twist needs to be for your short 308, I don't know.

 

[liltank]

Run the 135 SMK. It will get you to 600 and do well in your barrel regardless of the length.

 

[Kodiak99317]

What you have is a SR type barrel in 308. Try the old std., 40g of h4895, 210M and a 168g SMK bullet soft seated to the lands and tell us how it did. I shot 308 with 154g FB for about 10 yrs in HBR comp and it had a 1:14. N135 at 39.7 g did well too.

125 to 150g will shot best with your 1:14 and the magic barrel length in SR is like 20 1/2" or 21 1/2" if my memory is any good, makes for. A more rigid barrel...

 

[Jonny]

Thanks for the replies. My original post may have been a little misleading; I don't intend to be using subsonic loads. When I said "sub 600m" I meant shooting at 600m and below.

We got this twist originally as we intended to use 155s at the heaviest.

It seems like a 20" tube with this twist should still be adequate for 155s and below.

We use N140 at the moment but going to something slightly faster seems sensible.

 

[freepistol]

With a 14-twist barrel, you may be pretty limited as to what you can stabilize, on paper at least. That twist rate is not going to be optimal for projectiles in the 175 gr range and above, even at 28", so going shorter may put you at a further disadvantage. Generally, people doing what you are attempting want to use a fairly heavy projectile (at least 200 gr to much heavier/longer) with a fast twist barrel (10-twist or higher) and keep them inside 300 yd or so. Not saying you can't make it work, but a 14-twist barrel would be pretty restrictive in terms of projectile length (weight) even at 28" length, so you'll probably want to start out with something in the lighter (shorter) range. Not sure how well lighter pills are going to pan out while still keeping them subsonic, but you can always try.

Optimally, a 10-twist or faster with long heavy projectiles would be the better way to go.

I have a hard time remembering how to spell "bullet." Is it no longer PC to use "bullet" so now I have to learn how to spell "projectile?" :'(

 

[tdoyka]

proj.....prot....praj...pret....darn it!!!!! bullet, i spelled it!!!



6.5 creedmoor, 16 1/4" mgm barrel, 1 in 8" twist, 120 gr ballistic tips, i wouldn't worry about it

 

[freepistol]

If you really want to make it easy on yourself, type "pill" and call it a day ;D .

How would it sound on the evening news if it got out we were using pills to kill animals.

 

[tdoyka]

i gave my dog a pill, and she still asleep. been that way for a whole day. i took one and i'm feeling sleeeeeeee..... ;D

 

[Pappy83]

We have a 1-10 twist 14.5 inch barrel with fixed brake to make it legal. It shoots 175smk great a 600yds I have seen it shoot high 180's and low 190's on a ftr target. I think you will be surprised how little velocity you actually drop. We still can load that barrel to get near 2600fps with the 175's its hot but not excessive. My kid will be using a 26 inch barrel for 215 bergers again this year in f class better to have a heavier barrel then a lighter long one I believe. Just pick a bullet your rifle liked before and start there.