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

[Hecktic]

What are some pros & cons of the 16 vs. 18 inch barrel on an AR? I am looking to get an AR in a couple of months and I wanted to know what were some advantages & disadvantages of the 18 inch barrel compared to the standard length of regular ARs.

[SuperSet]

Primarily, the 18" barrel buys you the rifle length gas system, which will feel softer to shoot. Additionally, you'll have a little bit more muzzle velocity and that'll come into play if you are shooting match ammo at smaller targets 300y>.

[BucDan]

Interesting, usually the question is 14.5" vs 16". But it would depend on what you are using it for. If it is just a range gun, the 16 will serve you well. Now if you were benching the gun, then the 18 will work nicely for the FPS.

[BigBamBoo]

The whole FPS loss or gain is really very minimal. I have a 14.5,16,and 18"...and recently sold a 20".

Shooting the same ammo through the three rifles over my chronograph showed a avg. of 35 FPS less with the 16" vs the 18" and a avg. of 90 FPS less with the 14.5".

So as you can see....even the difference between the 18" and 14.5" is not any kind of "deal breaker" IMHO.

Now the difference in handling is night and day with the 14.5" being super handy and fast on target.
Remember that even though the BARREL is a given length, you have anywhere from 1" to 3" extra length depending on your muzzle brake or flash hider your using.

And then there is your gas tube length....this is a non issue with my rifles as all of them has adjustable gas blocs and I "tune" them so they have very slow bolt velocity.

Take care,Stan

[Hecktic]

What is FSP?

[freonr22]

Hav had a 20, 14.5, 16 1/12, 1/7, 1/9 respectively. My future will be a 1/8 18" for my plinking Wish I would have done it sooner.

[gemini1]

The velocity of a 55 gr M193 on a 16" barrel is 3132 fps, the 20" barrel is 3259. So its 127 fps for that 4" difference, which makes it 63.5 fps difference for an 18" barrel.

[motorwerks]

Originally Posted by SuperSet

Primarily, the 18" barrel buys you the rifle length gas system, which will feel softer to shoot. Additionally, you'll have a little bit more muzzle velocity and that'll come into play if you are shooting match ammo at smaller targets 300y>.

I feel like I see most in Midlength

[BigBamBoo]

Originally Posted by Hecktic

What is FSP?

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

Originally Posted by gemini1

The velocity of a 55 gr M193 on a 16" barrel is 3132 fps, the 20" barrel is 3259. So its 127 fps for that 4" difference, which makes it 63.5 fps difference for an 18" barrel.

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

[reidnez]

Originally Posted by Hecktic

What are some pros & cons of the 16 vs. 18 inch barrel on an AR? I am looking to get an AR in a couple of months and I wanted to know what were some advantages & disadvantages of the 18 inch barrel compared to the standard length of regular ARs.

Just to clarify...14.5" is actually standard for a carbine, i.e. military M4 spec. But that means you need a 1.5" (min) muzzle device permanently attached, in order to comply with the minimum legal barrel length of 16". 16" barrels are a little more popular on the commercial market because they allow you to remove or swap out the muzzle device without legal issues.

18" barrels can come with mid-length or rifle-length gas systems; both seem to work fine. Using a rifle-length, the gas port size needs to be a bit larger than it would be with a (M16-standard) 20" barrel.

As for my recommendation, it all depends on your intended use. The difference in performance (as others have noted) is pretty minor. For plinking, carbine classes, etc. I would go with a short barrel, as the longer ones come with a handling penalty and won't give you any benefit <300yds. If you want something to mainly shoot off a rest skip the intermediates and go with a heavy, 20" (or longer) barrel.

[Hecktic]

Originally Posted by gemini1

The velocity of a 55 gr M193 on a 16" barrel is 3132 fps, the 20" barrel is 3259. So its 127 fps for that 4" difference, which makes it 63.5 fps difference for an 18" barrel.

Got it, thanks for the exapmle. I understand fsp better now. I think I'm going to go with the 18' barrel. Does anyone have a good recommendation? I was looking at the Larue PredatAR, the Stag 3g or the Noveske Rouge Hunter.

[Hecktic]

Correction... feet per second

[SuperSet]

You have good taste as those are all excellent. What's the purpose of your build? SHTF/HD, 3-Gun, Precision/High Power, Plinking?
I run 18" Noveskes for my 3-gun uppers and they have been excellent. One even survived a Kaboom and still shoots MOA with 77gr SMKs. White Oak also makes excellent barrels although they don't last as long from my experience.

[Hecktic]

I will definitely consider getting an adjustable gas block. Thanks Stan

[Hecktic]

I’m thinking most of my shooting will be precision/high power & plinking. I will probably put a nice scope on it and use it for distance shooting.

[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]

Originally Posted by reidnez

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]

Originally Posted by Hecktic

I’m thinking most of my shooting will be precision/high power & plinking. I will probably put a nice scope on it and use it for distance shooting.

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]

Originally Posted by BigBamBoo

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]

Originally Posted by slo5oh

....still a 600 yard limitation.

600 yard limitation? What makes you think that?

[BigBamBoo]

Originally Posted by slo5oh

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.

[Exdc]

Originally Posted by 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!

Not to start an argument, but it has been stated (in several places, both here and on other forums... I can find and link them if you would like) that a SHORTER barrel will be more accurate, because the barrel is more rigid. They used fancy words like "resonance" and "harmonics" but those aren't really necessary to explain the general concept. Length does play a role in accuracy; it's just the opposite of what most people would think.

[Hoop]

A short stiff barrel will be potentially more accurate than a long skinny one. However if you have two lengths of similar material and profile the difference will be negligible at best.

There are people who make 223 go to 1k yards however they are using long barrels and bullets which cannot be loaded to mag length.

[sigma6]

Im going with an 18in "SPR" with as my first and only .223/5.56 AR. I am not sure which twist, probably a 1/8. My reason is im going to be plinking with it 95% of the time on a bench. If the off chance I do compete with it, it will really shine with the heavier match ammo.

Since its not a duty/HD weapon why would I need it too be light and maneuverable?

[tacticalcity]

It is all about how you will be using it. Shorter length barrel makes it easier to maneuver in tight spaces. Longer barrel assists will velocity at longer distances. So CQB guys go with 16 inches or even shorter. But a precision shooter would go with 18 or longer. Both can be used for the other purpose, it's only 2 inches. But it is 2 inches you will notice in a head to head comparison. Particularly in CQB usage.

My M4 upper has EXACTLY 16.1" inches of barrel and hinder together, as they are pinned and welded together so you get it as short as possible and be legal. Most are around 17+ inches when not pinned and welded. Running CQB courses that little difference is something I actually notice when switching between my M4 and my backup rifle with the standard length. I've gotten so used to the shorter length and the benefits that come with it, I am down right clumbsy with the standard 16" upper. I cannot imagine how difficult it would be for me to adjust to an 18" upper when running and gunning in a kill house. You could definitely do it, but you do notice the extra length and do have to adjust for it.

Long range guys will make just as strong of an argument that when reaching out there to make those long range shots, the shorter barrel can make the shots but the loss in velocity can mean the difference between a stopping shot and just a wounding shot. So while a 16" rifle with the same quality barrel and quality ammo can make the same shots they might not be as lethal at the outer limits of the rifles capabilities.

Knocking into walls more often with the 18" barrel is easier to notice when training than loss of velocity in a 16 upper. Since you are shooting targets, and not hostiles. So the question becomes, which is more practical for how you will be shooting. Are you gonna run and gun and take CQB type courses or are you going to use it primarily on the range making longer distance shots?

[tacticalcity]

Originally Posted by sigma6

I'm going with an 18in "SPR" with as my first and only .223/5.56 AR. I am not sure which twist, probably a 1/8. My reason is I'm going to be plinking with it 95% of the time on a bench. If the off chance I do compete with it, it will really shine with the heavier match ammo.

Since its not a duty/HD weapon why would I need it too be light and maneuverable?

Sounds like the right rifle for how you plan to use it.

However, bear in mind there are shooting schools all over CA that offer run and gun CB style courses...and they are EXTREMELY fun. Watch one of their videos and you may find that you actually want to take a course like that. Especially since they usually run just $160 per course.

You will still be able to use the SPR rifle for a CB course. It is not so different that it will not still be an enjoyable and successful experience for you. Just temporarily ditch the magnified optics and anything like bi-pods that weight it down but don't serve a CB purpose. After the course you can put them back on it and turn it back into a bench rest queen.

I'm not saying to change your rifle choice. I'm just saying don't rule out taking a course. It is an extremely fun way to spend a day at the range.

[phish]

Originally Posted by Exdc

Not to start an argument

you opened the door...

[jonzer77]

Originally Posted by Exdc

Not to start an argument, but it has been stated (in several places, both here and on other forums... I can find and link them if you would like) that a SHORTER barrel will be more accurate, because the barrel is more rigid. They used fancy words like "resonance" and "harmonics" but those aren't really necessary to explain the general concept. Length does play a role in accuracy; it's just the opposite of what most people would think.

Not if you reload.

[Iskra]

If you sling it muzzle-down behind your hip, anything longer than 16" will be in the dirt when you kneel down. Like to glass for pigs, or talk to kids at a checkpoint.

If its only ever going between your car and a bench, get whatever you want.

[mif_slim]

Originally Posted by Hecktic

What is FSP?

For Sale, Pending


jk.

18" like mention would have a softer recoil, not that there's a lot of recoil in the 5.56/223 but, it does play a roll when your trying to get on target for the follow up shot. Its not noticeable when shooting 1 shot per second, but it is when doing rapid fire or control pair...youll feel it.

[helpme]

Originally Posted by Hecktic

What is FSP?

This is GOLD!