How big a difference is Barrel length?

[fivepointstar]

I'm trying to pose this question right, I just can't find the words (sorry lack of sleep).

When it comes to AR15, how big a difference is the 16" bbl and the 20" bbl when it comes to accuracy?? When all the conditions are the same such as the same rifle, ammo, optics, free float etc etc....how much more accurate is an AR15 with a 20" then a Carbine length AR15?

Does the 4" really make a significant difference.

How significant is the difference in accuracy??

Thanks!!!

 

[BradMacc82]

I couldn't quantify it into numbers for you, but if everything was the same, the 20" in theory would probably still edge it out in accuracy.

Although my 16" barrels have shown to be quite accurate in the past.

The real difference would be in velocity differentials.


ETA: I'm in process of building a 20" for my brother and sister in law, so once that's done I'll try to do a head to head comparison for you.

 

[Mark75H]

Brad, I hope you get a chance to do the comparison at close and long distances.

 

[FrankOceanXray]

A wonderful article was linked in the active AR Pistol thread. Tests were done on the same gun... They just cut the barrel down. The numbers were impressive.

 

[Atec]

I couldn't quantify it into numbers for you, but if everything was the same, the 20" in theory would probably still edge it out in accuracy.

Although my 16" barrels have shown to be quite accurate in the past.

The real difference would be in velocity differentials.


ETA: I'm in process of building a 20" for my brother and sister in law, so once that's done I'll try to do a head to head comparison for you.

Will you adopt me ?

 

[jawn]

It's mostly the added velocity which makes it a slightly flatter shooter at distance.

 

[Numidian]

Barrel length has no bearing on accuracy. It has an effect on velocity though.

 

[Boom Boom]

The question, as posed, is flawed. For example, a high-quality 16" barrel is typically more accurate than a low-rent 20" barrel out to any distance. Are both barrels HBAR, standard, or pencil? Are they 4140 CL, 4150 CL, or stainless? Are they the same manufacturer? Is the twist rate the same? Are they chambered for .223, 5.56, or .223 Wylde? Are you using match-grade or game ammo (like Black Hills), bulk, or something in between? All these variables determine accuracy.

 

[Jimbob2.0]

I would say virtually none, but to do a true side by side you would need two barrels from the same maker, same twist etc and in all likelyhood the differences in manufacturing consistency would be more of a factor. The benefits of a longer barrel are velocity, stabilization of the projectile and recoil, and recoil isnt an issue for .223 (really) in semi-auto. 16" is plenty in most cases to stabilize a bullet with a reasonable twist, and I would suspect the difference in velocity would be minor.

I have been dumping all of my 20" rigs in favor of 16" government profile guns.

 

[fivepointstar]

I'm trying to pose this question right, I just can't find the words (sorry lack of sleep).

When it comes to AR15, how big a difference is the 16" bbl and the 20" bbl when it comes to accuracy?? When all the conditions are the same such as the same rifle, ammo, optics, free float etc etc....how much more accurate is an AR15 with a 20" then a Carbine length AR15?

Does the 4" really make a significant difference.

How significant is the difference in accuracy??

Thanks!!!

The question, as posed, is flawed. For example, a high-quality 16" barrel is typically more accurate than a low-rent 20" barrel out to any distance. Are both barrels HBAR, standard, or pencil? Are they 4140 CL, 4150 CL, or stainless? Are they the same manufacturer? Is the twist rate the same? Are they chambered for .223, 5.56, or .223 Wylde? Are you using match-grade or game ammo (like Black Hills), bulk, or something in between? All these variables determine accuracy.

I said "all conditions are the same"
Thats why I'm looking for answers?

 

[fivepointstar]

I would say virtually none, but to do a true side by side you would need two barrels from the same maker, same twist etc and in all likelyhood the differences in manufacturing consistency would be more of a factor. The benefits of a longer barrel are velocity, stabilization of the projectile and recoil, and recoil isnt an issue for .223 (really) in semi-auto. 16" is plenty in most cases to stabilize a bullet with a reasonable twist, and I would suspect the difference in velocity would be minor.

I have been dumping all of my 20" rigs in favor of 16" government profile guns.

Interesting....

this is what I've been considering as well.

 

[byf43]

I've got a Colt AR-HBAR with 20" 1:7 twist, and using my handloads and Sierra 69 gr BTHP 'boolits', it'll shoot 3 shots that can be covered by a dime, at 100 yards.


I've just ordered a Colt's LE 6721 w/ 16" 1:9 twist barrel, and after I get it, I do plan to run an accuracy test to see how it performs with the same load.
(I 'fretted' over the difference between the LE6920 and the LE6721 for quite a while. The fact that the 6721 is 'cash and carry' swayed my decision.)

Push come to shove, I may just find a good 16" HBAR 1:7 twist barrel.
(I even thought about having a top-end built the way I want it.)


I've always been interested in shooting those nice, tiny groups.
I suppose that comes from my High Power Rifle days.

 

[K31]

Barrel length may have no effect on accuracy, but the sight radius of an HBAR is going to be longer than on an AR with a M4 profile.

 

[Yoshi]

With optics, longer barrels are not more accurate. However, velocity will be impacted to a degree when you go to a shorter barrel. So, a little less wind drift with the longer barrels.

 

[Mark75H]

Disinformation abounds ... unsubscribing

 

[huesmann]

Maybe the additional velocity isn't that big a deal, but given higher velocity, isn't that going to translate to longer range, and therefore more accuracy (at long distances)?

 

[BenL]

Hopefully, Ed will come along and give you the definitive answer.

 

[Biggie313]

They always tell me size doesnt matter

 

[Yoshi]

Disinformation abounds ... unsubscribing

Enlighten us then.

 

[obsolete]

There has been a lot of discussion on this topic in the bolt gun world over the last ten years. Many folks have gone from 26" to 18-20" barrels and actually gained a little accuracy due to less barrel whip. The trick is picking the right length for your application. For instance, if you are considering using a bullet at the very limit of it's supersonic range......say a 168 FGGM at 1000-1100 yards, then the longer barrel will serve you better as velocity becomes very important.

(Meaning cut and recrowned the same barrel)

A pretty decent article on cutting bolt gun barrels for tactical work -

http://www.tacticaloperations.com/SWATbarrel/