308 barrel length

[JMP]

24"+
1:12" twist
5r rifling
no fluting

If someone tells you differently, they don't know beans about guns unless it's an AR-10.

[Gem1950]

https://www.youtube.com/watch?x-yt-cl=84503534&v=RFhM0NHsYLk&x-yt-ts=1421914688#t=126

[Jarhead]

With today's ammo I doubt barrel length is as important as it once was, especially at ranges under 600-700

[five.five-six]

24"+
1:12" twist
5r rifling
no fluting

If someone tells you differently, they don't know beans about guns unless it's an AR-10.

I read a good writeup that put it at 21.5" biased on barrel harmonics at 2,700 FPS or something like that.


Of course, OP's sales person could be right, that would explain why SBRs are illegal. If 18" is faster, a 6" barrel has even less drag.

[toby]

24"+
1:12" twist
5r rifling
no fluting
.

I would not put a big emphasis on the 5r and the fluting won't hurt but what do I know?

[FMJBT]

Thanks for the info. I was at a shop looking for 308 to shoot in the range of 300-700 yards and that's what this guy recommended. It did not seen right at all to me but I figured I'd ask to verify.

Depending on how much you intend to carry the rifle, an 18" barrel might very well be optimal for shooting 300-700 yards. Obviously longer barrels will give you better velocity, but past about 22" you reach a point of diminishing returns where the velocity may not be worth the weight penalty.

The Truth About Guns did an interesting experiment with barrel length on a little over a year ago that sheds some light on how different 308 loads respond to shortening a barrel from 26" down to 18", 16" and finally 13.5". This velocity table is from that article:



Article:

http://www.thetruthaboutguns.com/2013/10/daniel-zimmerman/the-truth-about-barrel-length-muzzle-velocity-and-accuracy/

[vintagearms]

24"+
1:12" twist
5r rifling
no fluting

If someone tells you differently, they don't know beans about guns unless it's an AR-10.

Would 11.25 or 1 in 10 be better or not?

[JMP]

I read a good writeup that put it at 21.5" biased on barrel harmonics at 2,700 FPS or something like that.


Of course, OP's sales person could be right, that would explain why SBRs are illegal. If 18" is faster, a 6" barrel has even less drag.

Unfortunately, I do not believe that the folks on the internet that write about barrel harmonics have even taken a remedial university course on harmonic motion, waves, or oscillations. These dynamics change dramatically with the contour of the barrel. It is extremely difficult to calculation the moment inertia of a tapered barrel. Usually, they use a cylindrical barrel to simplify calculations.

But, you are right, an AR-10 pistol will probably go a mile, maybe two.

[JTROKS]

LOL! 18". Just like a an arm brace still legal to shoulder as long as I don't make modifications to it. Simply amazing.

[milotrain]

With today's ammo I doubt barrel length is as important as it once was, especially at ranges under 600-700

Funny, I'd think that with today's smokeless powders you could actually utilize a much longer barrel. But agreed, that under 600-700 yards I doubt it's much of a difference at all.

[postal]

With today's ammo I doubt barrel length is as important as it once was, especially at ranges under 600-700

Several things going on here.....

1- a short fat barrel is stiffer- which is generally considered inherently more accurate.

2- even todays powders.... longer barrel = higher velocity.

3- velocity is GOOD. More vel, more good.

4- more vel = longer range before hitting transonic.

so... if you only intend on getting to 5-6-700.. a short barrel is fine.

If you get the right bullet weight/high BC... and the right barrel length... you can get 1000-1,100 yds with the same rifle easy.

It comes down to
1 purpose (handiness/weight)
2 distance

If you dont think barrel length is important, look at self defense ammo from short barreled pistols, and they dont have enough vel to reliably open up compared to a full size pistol.... we're talking about a 3.5 inch barrel compared to a 5 inch gun..... a whopping 1.5 inches makes a significant difference in handgun ammo performance.........

Besides.... the longer the barrel.... the closer you are to your target.... making your shot that much easier.

[JMP]

I was told today at a shop that the ideal barrel length for a 308 is 18". Anything longer than that causes drag on the bullet slowing it down. Anyone ever hear that?

Botton line is the gun shop guy doesn't know beans. Go back, and tell him that you have someone willing to bet him $1,000 that is claim is false. We can chrono his 18" vs. my longer barrel. Please tell him to make sure he brings the cash with him.

[five.five-six]

Botton line is the gun shop guy doesn't know beans. Go back, and tell him that you have someone willing to bet him $1,000 that is claim is false. We can chrono his 18" vs. my longer barrel. Please tell him to make sure he brings the cash with him.

Um, have you ever seen the inside of a barrel? It's covered with copper, copper that rubbed off of the bullet as it went down the tube part. That my friend is FRICTION, and friction always slows things down. What they need to do is drill out the barrels a little bigger than the bullets so there would be less friction, then your 24" barrel would go faster.

You're welcome.

[postal]

HAHAHAHAA!!!!!!!!!!!^^^^^^^^

So if I had a 308 'pistol'.... and the 'barrel' ended at the end of the throat.... no copper, no friction.... I'd smoke EVERYONE!

I'm taking JMP's $1k!!!!!

[nrakid88]

If you read this entire article... you will find it was about accuracy not velocity. Loads were tweaked for each barrel length, not for the highest possible velocity, but for group size. So just posting the velocity info is a little misleading, but not much.

Very good article.

http://www.thetruthaboutguns.com/2013/10/daniel-zimmerman/the-truth-about-barrel-length-muzzle-velocity-and-accuracy/

Depending on how much you intend to carry the rifle, an 18" barrel might very well be optimal for shooting 300-700 yards. Obviously longer barrels will give you better velocity, but past about 22" you reach a point of diminishing returns where the velocity may not be worth the weight penalty.

The Truth About Guns did an interesting experiment with barrel length on a little over a year ago that sheds some light on how different 308 loads respond to shortening a barrel from 26" down to 18", 16" and finally 13.5". This velocity table is from that article:



Article:
http://www.thetruthaboutguns.com/201...-and-accuracy/