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View Full Version : difference in accuracy from an upper 14.5 to 20 inches?


dancinzen
06-19-2010, 2:47 PM
hello,

i am just wondering who really knows the true pros and cons of ar-15 barrel length... i mean what is the real difference in accuracy from a 14.5" pinned upper to a 16", and the 16" to an 18", and an 18" to a 20". and besides accuracy what else is lost in a shorter barrel? i am wanting to build 3 uppers, and i am thinking of a 14.5 pinned for a kisser out to 50 to 200 yds, a pencil lightweight 16" upper, and a heavy spr in 18 or 20(lightest possible without losing alot of accuracy). i am just thinking of all shtf situations and what three ar's i would want... what would you recommend?

pepsi2451
06-19-2010, 2:49 PM
With a shorter barrel you will lose velocity not accuracy.

AlliedArmory
06-19-2010, 2:56 PM
With a shorter barrel you will lose velocity not accuracy.


+1...

dancinzen
06-19-2010, 3:07 PM
ok so what does this mean in laymen's terms. for example, what will the difference be from a 14.5" to a 16" barrel?

nrakid88
06-19-2010, 3:09 PM
It will affect your terminal results. The 20 inch will put more hurt on what it hits. Instead of getting three diferent 5.56 guns that will all be equally unimpressive, you could get on 5.56 and a .308. That will cover much more ground than three of basically the same gun. Or you can do like me, sell all your rifles for a 6.8 and reloading equipment, and have one gun that thinks it can do it all.

thayne
06-19-2010, 3:44 PM
It will affect your terminal results. The 20 inch will put more hurt on what it hits. Instead of getting three diferent 5.56 guns that will all be equally unimpressive, you could get on 5.56 and a .308. That will cover much more ground than three of basically the same gun. Or you can do like me, sell all your rifles for a 6.8 and reloading equipment, and have one gun that thinks it can do it all.

or get a 5.56 and a 6.8 upper :D

bjl333
06-20-2010, 1:42 AM
With a shorter barrel you will lose velocity not accuracy.

+1...


+2.....

1988
06-20-2010, 3:02 AM
It depends on the construction of the barrel.

Barrel length, twist rate, barrel contour, and construction quality can play pretty good tricks on the precision/accuracy.

Barrel length alone does not dictate the precision or accuracy of a rifle.

Manic Moran
06-20-2010, 8:29 AM
With a shorter barrel you will lose velocity not accuracy.

Why do I not see many 14.5" barrels at Camp Perry, then? Terminal results are pretty irrelevant for a paper target.

In effect, velocity will become accuracy. Even though the dispersion rate may be exactly the same between the two barrels, the faster bullet will have less time for elements to have an effect on it. It will also have a flatter trajectory, making superelevation calculations less critical. OK. I'll grant you mechanical accuracy will not be any worse. Practical accuracy will be.

NTM

LloydXmas250
06-20-2010, 8:40 AM
I always thought longer barrel, longer sight picture so better accuracy. Of course that's really only when you use irons. Like everyone said, velocity will be lower with a shorter barrel but how much of a noticeable difference will there be between 14.5" and 16"? I wouldn't imagine too much. It would probably matter if you're shooting for competition but if you're just a weekend warrior like most of us it probably won't matter and will a lot lighter with the shorter barrel.

dancinzen
06-20-2010, 1:04 PM
thanks for the input everyone...

ar15barrels
06-20-2010, 1:41 PM
ok so what does this mean in laymen's terms.

It's easier to hit with a longer barrel.
It's not the accuracy that makes it easier.
It's the sight radius and velocity.

The reason you don't see 14.5" barrels at camp perry is that the 20" barrels give superior velocity which is very important in the wind.
The 20" barrels also have a longer sight radius which makes it easier to hold the sight picture in a more repeatable way.

Mail Clerk
06-20-2010, 2:30 PM
I always thought longer barrel, longer sight picture so better accuracy. Of course that's really only when you use irons. Like everyone said, velocity will be lower with a shorter barrel but how much of a noticeable difference will there be between 14.5" and 16"? I wouldn't imagine too much. It would probably matter if you're shooting for competition but if you're just a weekend warrior like most of us it probably won't matter and will a lot lighter with the shorter barrel.

I totally agree:D

Mail Clerk:)

xxINKxx
06-20-2010, 2:43 PM
I always thought longer barrel, longer sight picture so better accuracy. Of course that's really only when you use irons. Like everyone said, velocity will be lower with a shorter barrel but how much of a noticeable difference will there be between 14.5" and 16"? I wouldn't imagine too much. It would probably matter if you're shooting for competition but if you're just a weekend warrior like most of us it probably won't matter and will a lot lighter with the shorter barrel.

Im a weekend warrior like yourself. I go blast away at the range, and wreak havok in the desert. I saw no real difference between 16" and 14.5" barrel when shooting out there.

I had Randall (ar15barrels) cut mine down a lil over a month ago and im very happy, saved a lil bit of weight, and shorter length feels better to me. I cant say shorter barrel will be good for everyone. But for what the average person does (range/desert) its very nice and really no noticable difference.

slappomatt
06-20-2010, 3:46 PM
Truly theoretically a shorter barrel all things equal should be MORE accurate because it will be stiffer. In the real world its another story as has been mentioned.

Jpach
06-20-2010, 4:58 PM
OK. I'll grant you mechanical accuracy will not be any worse. Practical accuracy will be.

NTM

How is a competition at Camp Perry considered practical?

Along with what Randall said, I think the majority of 14.5" ARs are chrome lined and as a result do not have the BEST accuracy. It seems people get 14.5" guns simply because they are light, are not so cumbersome, and they do what the shooter wants them to do: work on every shot and go bang.

Manic Moran
06-20-2010, 7:43 PM
How is a competition at Camp Perry considered practical?

It's a real person shooting at a distant target in real weather conditions.

It's not a rifle being fired remotely from a vice at a relatively short, indoor range to determine dispersion.

Competition is a perfectly viable purpose for a firearm.

NTM

daveyshooter
06-20-2010, 8:16 PM
maybe it's me, but I hear a louder noise from my 16" AR15 barrel than from my 20" barreled one.

slappomatt
06-20-2010, 10:24 PM
Yeah a shorter barrel will be louder. I used to have a 11.5" pistol AR and that thing was LOUD!!!

ar15barrels
06-20-2010, 11:27 PM
maybe it's me, but I hear a louder noise from my 16" AR15 barrel than from my 20" barreled one.

The muzzle blast is directly proportional to gas pressure at the muzzle.
The longer the barrel, the lower the pressure when the bullet leaves the barrel.
Also, the shorter the barrel, the closer to your face the blast is being generated.