I'm contemplating what the best combination of barrel length and twist rate would be for long distances (500-600 yards).  Granted, a lot of this will depend on what ammo is used.  I haven't selected what I want to use yet, but for the sake of argument let's say a 75 grain boat-tail bullet.

I'm debating between a 20" and a 24" barrel, and a 1/9 or 1/12 twist rate.

Currently my thoughts are on a 24" 1/12 barrel, but I wanted to see what you guys think.

Right now I'm looking to be inside a sillouette out at 500 to 600 yards.  I'm not specifically seeking groups the size of a dime, nickel, quarter, etc., but I wouldn't turn down that kind of accuracy.  As I said my goal is to be in the sillouette at those distances.

Do you guys think my above selection is the best choice, or what else would you suggest?  Is there any location where I can read a report on someone's experiment with this sort of situation?

Thanks for your help!

_MaH

If you are going to shoot 75 grain ammo I would go with a 1/8 or 1/7 twist.

1/12 for 75gr?  

If you're only gonna shot 35/40/50 gr varmit loads, it would be fine.

If you're not gonna shoot 69gr+ all the time, then 1/9

If you're only going to shoot 69+, then 1/8 or 1/7.

Barrel length doesn't really matter for accuracy, except that you'll get more velocity, so you won't be aiming so far in the sky...

18-22" should be fine...  pick the profile and length you want for utility purposes first (carrying, storage, balance, etc...), then barrel length for velocity second...

To the post above 55gr FMJ won't stabilise in 1/12?

Of course it will.  1/12 is the twist for the M16A1 with 55 grain FMJ.

To the OP you will want 1/8 or 1/7 twist for the 75 grain bullet.

Thanks for your help, everyone!  I was unaware that I would need a faster twist rate for a heavier bullet, but now that I think about it, it makes sense.

Learn something new every day!

Again, thanks!

_MaH

with a 1/12 the 75grainer will be keyholeing at 100 yards.

Quoted: Thanks for your help, everyone!  I was unaware that I would need a faster twist rate for a heavier bullet, but now that I think about it, it makes sense. Learn something new every day! Again, thanks! _MaH

The need 4 a faster twist rate has less 2 do with weight and more to do with length...

my vote?  20 inch 1\8

Mike

A combination that has been proven out very thoroughly is this one:

Krieger 1/8" twist (or PacNor, Hart, Douglas, Lilja,...even a Wilson)
24" to 26" long (mine is 26")
Wylde chamber

24.0 gr Varget
80 gr Sierra MatchKing seated 0.010" off the lands
Federal 210M
Winchester case

This will get you to 600 yards with great accuracy

What Mike said ...

Krieger 1/8" twist (or PacNor, Hart, Douglas, Lilja,...
24" to 26" long (mine is 26")
Wylde chamber


> Now it,s just bring able to fine the Krieger barrel.. I would like to have a Service rifle contour 20in barrel length. I think Compass Lake is out of them