Pros & Cons of a 16 inch barrel vs. 18 inch barrel for an AR Question?

[slo5oh]

There's a LOT of small differences. If you google it you can read the subject to death. The key is that longer barrels will give you more muzzle velocity. The most important thing is to read all you can on the subject, it's your $.
The short and sweet on barrel lengths IMHO:
14.5" : nice short barrel, but in cali you'll need a muzzle break long enough to make it equal length with a 16" anyhow, so why bother?
16" : Perfect if you want that short barrel M4 look, capable of putting a round out to 600 yards given a tighter twist (1/7) and using heavier ammo. (Of course someone will argue that their 1/9 is a nail driver at 600 yards, this is of course MY opinion)
20" : Somewhere between 100 and 200 more fps (feet per second) muzzle velocity so you will have less bullet drop aka a "flatter trajectory" to compensate for at farther ranges, still a 600 yard limitation.

18" : somewhere between a 16" and 20"

Don't let ANYONE tell you that a longer barrel is "more accurate" than a shorter barrel. Accuracy has nothing to do with it. Once you go past 200 yards it's all about calculating for bullet drop, I forget the exact numbers (google help me!) but at 600 yards it's something like 36" for a 20" and 60" for a 16". So long as you KNOW the bullet drop both barrels are just as accurate.
You want to really get going ask about barrel twists!

[slo5oh]

whoops, double tap.

[reidnez]

Precision and plinking are two totally different uses that demand totally different weapons...you want a light, short carbine (14.5" or 16", standard or pencil profile, <7lbs, preferably) for shooting offhand. For precision shooting from a rest, you want a heavy-profile, 20" or longer barrel. Weight is actually an advantage here; sniper rifles tend to be at least 10lbs, competition benchrest rifles are often double that. Heavier barrels are stiffer and thus potentially more accurate, and the greater inertia of a heavy weapon resists the shooter's natural movements.

You can't have it both ways. Sure, you can compromise and have a weapon that's reasonably adequate for multiple tasks. But there really is no "jack of all trades" configuration. In my opinion it is preferable to design a weapon for a specific use. It's so easy to swap uppers...since you're considering some high-dollar brands, why not build a nice precision rig and a cheaper plinking/all-purpose rig? You could build a perfectly decent plinking upper for ~$600, perhaps less if you get a pencil barrel since they are out of vogue these days (despite their light weight and excellent handling.)

[ExtremeX]

16 vs 18 is negligible if we are talking apples to apples barrels, small gain in FPS, but you add length and increase your swing weight which is important to a lot of shooters.

I wont say one is more accurate than another, because you can get a 16" with a heavier profile barrel which would probably outshoot a run of the mill 18". You should take some time to understand barrel profiles and materials used to make them. For example chrome lined steel vs stainless.

One member said 18 buys you a rifle length gas system which is available, but more commonly found is a midlength gas system.

Its the same thing when dealing with a 16" gas system, carbine vs middy.

Then we get into twist rates, 1:9. 1:8. 1:7. If you are serious about long distance shooting, then heavier match ammo is your friend, pick a twist rate which will be best for the loads you want to use. There is a big difference in the ammo I use for plinking and target shooting, along with a cost difference.

[ExtremeX]

Precision and plinking are two totally different uses that demand totally different weapons...you want a light, short carbine (<7lbs, preferably) for shooting offhand. For precision shooting from a rest, weight is actually an advantage; sniper rifles tend to be at least 10lbs, competition benchrest rifles are often double that. Heavier barrels are stiffer and thus potentially more accurate, and the greater inertia of a heavy weapon resists the shooter's natural movements.

You can't have it both ways. Sure, you can compromise and have a weapon that's reasonably adequate for multiple tasks. But there really is no "jack of all trades" configuration. In my opinion it is preferable to design a weapon for a specific use.

well said...

Its the reason lots of people on this forum have more than one AR. My target / precision setup consists of a 24" stainless bull barrel with a 1:8 twist for shooting heavier ammo. I shoot this rifle only from a bench.

Then a 16" chrome lined M4 profile barrel with a 1:9 twist for plinking with 55gr ammo.

[SuperSet]

For highpower and service rifle, those guys shoot 20" heavy profiles. I'd do the same if I were you. 3-gunners love 18" barrels due to the softer recoil impulse, good enough accuracy out to 400-500Y and easier to maneuver than 20" in close quarters.

[gemini1]

Not sure what FSP is????....oh...you mean FPS Feet Per Second....the speed that the bullet travels.




Are your #'s from shooting over a chronograph or generic tables? The only way to know for sure is shooting over a chronograph. And I have never seen it (bullet speed) linear like your suggesting.

Every load will shoot differently in different rifles due to chamber and barrel specs. Example a slower twist barrel is generally faster then faster twist twist barrel due to friction with a given bullet.

And again with the gas length system...get a ADJUSTABLE GAS BLOCK. Then it does not matter if it is a carbine length or rifle length. And you can tune your rifle to run very efficiently.

Take care,Stan

Nah, its just from generic table Stan. I've been told and have read about barrel lengths and velocities, and that there's not much fps gain between a 16 to an 18" when I was deciding which barrel length to get. And even from your input, it does confirm what I've read, which is why I ended up with a 16" barrel.

[EvolutionGSR]

Sounds like you can do what you want with a 16" barrel. I read somewhere once, and I'm sure most people here have read this, about getting the shortest barrel that will do the job. You can get a nice stainless 16" 1:8 wylde chambered upper that will be more accurate than you are until you get some time behind it.

[Hecktic]

I definitely have a better idea about barrel length and performance plus some additional information. This is my first AR (and probably won’t be the last). I’m looking forward to investing in a good solid rifle for my 1st purchase. I did a stint in the Army years back so I am familiar with the M16 and the AR platform.

I want to purchase my first rifle but my next project is going to be an AR build. I have a lot learning and reading to do but it will all come together eventually. I do like the idea of building rifles for various intended uses considering it is so easy to swap out uppers and I will apply that to future builds.

Anyway thanks for all your input and I welcome all your ideas, thoughts, opinions, and concerns because it helps me enhance my little knowledge about this. And I think for my next AR I will probably go with a 16 inch barrel.

[tonyxcom]

....still a 600 yard limitation.

600 yard limitation? What makes you think that?

[BigBamBoo]

14.5" : nice short barrel, but in cali you'll need a muzzle break long enough to make it equal length with a 16" anyhow, so why bother?

Because depending on your muzzle brake or flash hider it is still substantially shorter.

Here are a couple of pics of my 14.5" (with pinned FH to make it 16 1/4") and my 16". As you see it is almost 3" shorter. And that three inches makes a big difference in handling,etc.

As for barrel profile....heavy barrel vs "pencil" barrel. There are options out there that gives you the best of both worlds.

Inter JP barrels and their heat sinks. You get the weight savings and handling of a "pencil" barrel but the cooling capabilities that far exceed a heavy barrel.
Info here: http://www.jprifles.com/1.4.5_hs.php

Having owned 20",18",16",and 14.5" for a "do all" rifle it is hard to beat the 18". And set up right it really can take on a lot of different roles.
My 18" is currently setup with iron sights for the steel shoots we have here at the local club.
I use it out to 500 meters and it works well. Slap a scope on it and it is a solid 600 yard rifle using 75 or 77 grain bullets.


Take care,Stan







My "lean & clean" 18 incher

[artoaster]

In alot of ways the ammo you'll eventually purchase (bullet weight) should determine your choice of AR type/barrel.

One who buys cheapest 55gr at gun shows and surplus buys should get appropriate AR for plinking.

If you're willing to spend $ on the ammunition that will optimize your barrel then your priorities will reflect the type of AR you should build.

[Hoop]

Well, I have a 16" build with a leupold VXR 3-9. I like it a lot. However for distance shooting at targets I would want a longer barrel and a scope with more magnification and a parallax adjustment.

Also if you decide to compete in high power then it's high power configuration so 20" national match type rifle.

[slo5oh]

Tonyxcom, 600 yards from what I've read is considered the limit of a 5.56 round.
Bigbamboo,
A non threaded 16" barrel will sit nose to nose with a pinned 14.5 won't it? I understand what you're saying though and the comments above are my opinion, I would rather have a 16" barrel than a Cali pinned 14.5 made 16" because morons in office don't trust me. If I could build a real 14.5 I probably would.

[tonyxcom]

Thats interesting because I have shot 5.56 out past 750y, hell my brother was shooting right next to me with a 1-4x too.