AR15: 20" vs. 16"

[Blain]

Ok, finally got my friend to the gunshop today and he got a first hand look at an AR. It was a Bushmaster, 14" barrel version with a 2" long muzzle break on it.

He really liked how the rifle looked and felt. However, I have heard too many horror stories about the 14" M4s not having the power to knock a man down with one shot. So I convinced him to wait to look at the 16" and 20" version coming in this Friday.

My questions are the following:

How much of a velocity difference are there between the two barrel lengths?

How much more killing power does the 20" barrel give the .223 over the 16"? I have heard stories of the 20" causing much more damage to both men and beast than the 16" version. Have any of you noticed this, or if there is a difference at all?

I have also heard that from 0-300 yards the 16" is equal with the 20". Any additional info would be much appreciated, thanks.

 

[ocabj]

I'm not sure where you heard that 14", 16", 20" have varying "killing power." If someone pointed a loaded AR at my center of mass and pulled the trigger, I don't care what length the barrel is, I'm most likely going to die.

As far as accuracy is concerned, barrel length does play some factor, which is why you see 20" and sometimes 24" AR barrels in match competition. I'm not a competition shooter so I cannot be authoritative, but this should be true.

I do own a 16" pre-94 Colt Sporter HBAR Lightweight and I can tell you right now that I can get 1/2 inch groups at 50yds and 1 inch groups at 100 yds (with iron or Aimpoint Comp ML2), and I'm sure most other people can do the same or better with a 16".

If your friend is really concerned about barrel lengths, he can always get a 20" AR and get a 16" upper receiver / barrel to interchange (or vice versa). I myself was thinking about getting a 20" flattop upper receiver so I could mount a scope.

Just make sure he gets a quality AR variant and he will be happy with his purchase for years to come.

 

[thisaway]

I bought an Olympic Arms PCR99 which features a 16-inch barrel. I later purchased a DPMS upper receiver which features a 20-inch barrel. They are completely interchangeable on the lower receiver and I can tell little difference in accuracy between the two at 100 yards (my sight-in distance).

Your friend could go ahead and purchase the 14-incher and purchase a spare upper with a 20-inch barrel...this will likely increase his weapon's versatility, and should soothe any worries about hitting power.

 

[Nightcrawler]

The problem with commerical AR-15 20" models is that the barrels are heavy; heavier in fact, than GI (Colt or FN produced) M16A2s, and heavier than M16A1s by a wide margin.

What this makes for is a weapon that's unneccesarily heavy. I don't mind a 10lb rifle, I just don't like it when the rifle weighs a lot more than it should, if that makes any sense. A FAL is okay at 10lbs. An AR-15 20" shouldn't be more than eight, which is about what an M16A2 weighs. An M16A1 (my issue rifle in the Guards) weighs only about 7lbs, and is very handy. I miss the old triangular handguards, though. But call me old fashioned...

But, unless you're going to constrain all of your shooting to 200 yards an in, you're better off (ballistically) with a 20" barrel. .223 is a round that relies heavily on velocity and benefits much from a 20" or even a 24" barrel. I think the 20" model is the best all-rounder; long enough for great ballistic performance, but not overlong and unweildy like some of the race guns you see.

 

[DaveH]

However, I have heard too many horror stories about the 14" M4s not having the power to knock a man down with one shot.

Sounds like you need a crew-served weapon.

Carlos Hathcock told a story about a VC soldier that took four 30-06 and three 308 rounds. What finally stopped him was a headshot.

Blackhawk Down recounts several cases of drugged up baddies running away with multiple torso hits.

If survival is your motivation, practice will serve you better than faith in a magic bullet or barrel length.
Choose a rifle practical to your situation and practice.

 

[bad_dad_brad]

I don't like muzzle breaks. Too loud! And with a 14.5" barrel you will have a muzzel break to make it a legal 16". I prefer the carbine at 16". It is one pound lighter, much handier, and almost has the same energy as a 20" AR.

I am one of these days, going to get a 24" upper for target and varminting.

Just an FYI, some competitions require you shoot a 20".

I went with the Bushy 16" shorty A2 model and have been very pleased. If the dealer does not have what you want, have him order it for you. FYI the Bushy AK compensated 14.5" barrel is extremely loud!

 

[Blain]

Are there any brakes that are not quite as loud as the AK style one but still "cool" looking. He doesn't seem to want a naked barrel, no matter what.

 

[Gordon]

I have two Colt 20" and one M-4 upper on an Oly lower. I much prefer 20" except inside.

 

[Blain]

ME too, and hopefully he will too when he gets to see one on Friday. I hope he either goes for that or the 16"er.

 

[MK11]

Why not both? If it's the right model, you can just replace the upper with a longer or shorter barrel length down the road.

I like the 16" because I think a .223 as a personal defense rifle should be light and handy. Horror stories coming out of Afghanistan seem to be based partly on ammo that was designed to drill a neat hole through Warsaw Pact body armor instead of tumble and fragment in soft tissue. Barrel length may or may not have anything to do with it (although 14" does sound pretty short for a serious battle rifle). I'm just regurgitating some of what I've read, I have no professional opinion to offer.

On the other hand, if his primary focus is target shooting beyond 150 to 200 yards, the 20" is definitely superior. In which case, get the shorter barrel later.

 

[Onslaught]

Lots of good info on http://www.ammo-oracle.com/ . Like this chart for instance...

Distance to 2700 fps| 20" Bbl|-- | 16" Bbl|-- |14.5" Bbl|
M193 ------------------|190-200m | 140-150m|95-100m|
M855 -------------------|140-150m| 90-95m ---|45-50m|

2700fps is generally accepted as the minimum speed neccessary for reliable bullet fragmentation.

If your friend likes the looks of the 14.5" with a brake, I'd suggest he take a look at Rock River's fake-brake, which is a 16" barrel with a flash supressor pressed back so far that the barrel is even with the end of the FS, rendering it useless, and therefore legal. I have a friend who's got one of the M4geries with the Fake Brake from Rock River, and it is darn sweet.

 

[BigG]

The 223 only does its "magic" at high velocity. The little cartridge is tasked all it can take at 20". When you chop off the bbl you are just limiting it more than it already is, imho.

 

[Jeff White]

Horror stories coming out of Afghanistan seem to be based partly on ammo that was designed to drill a neat hole through Warsaw Pact body armor instead of tumble and fragment in soft tissue. Barrel length may or may not have anything to do with it (although 14" does sound pretty short for a serious battle rifle). I'm just regurgitating some of what I've read, I have no professional opinion to offer.

Have you seen any official reports, or are you talking about some of the anecdotal stuff that's floating around the internet? Reason I asked is that the Combat Development Branch at the Infantry School has made two trips to Afghanistan to get "lessons learned" information and they have received no complaints about lethality of M855 ammunition.

A lot of what's floating around out there is put out by people with an agenda. The complaints we are seeing are most likely attributable to the general lack of close combat experience of our troops rather then any great ineffectiveness in our service weapons and ammunition.

There is some work being done on a more effective 5.56mm round. This may increase the range at which the bullet reliably fragments. (by coming up with a bullet that will fragment at a lower velocity) But M855 and M193 are by no means inadequate combat rounds. People can be hard to stop. There are no magic bullets.

Jeff

 

[Bartholomew Roberts]

As others have stated, the magical "stop a man with one round" bullet has yet to be invented. I was reading in a forum the other day about a sailor who took a .50 BMG round in the hip due to a negligent discharge - he still managed to pummel the person responsible for said ND pretty well according to the doctor involved.

Check out the ammo-oracle link Onslaught referenced, it will help answer a lot of your questions I think.

I would advise against a 14.5" barrel just because the muzzle brake will have to be permanently attached. This can be a pain later down the road if you want to change muzzle devices or add other accessories (most types of free float tube require removal of front sight post - which you can't do with a permanently attached muzzle device).

As far as terminal ballistics, the 20" will give you more velocity than the 14.5" or the 16" and velocity is the key component that makes the 5.56mm effective. I find my 16" 1/9 just fine for my uses; but a 20" 1/7 would have a better effective range and be able to use the heavier rounds mentioned in the referenced link.

 

[meathammer]

I own an Armalite flat-top with 16" barrel. I originally wanted the 20", but couldn't find one at the time. Armalites aren't real easy to come by in my neck of the woods. (At least the one I wanted.) Anyway, I decided I could always purchase another upper (20") so this wasn't really a deciding factor for me. I do happen to like the carbine weight and length. I haven't really shot the rifle beyond 200yds., I use it mostly for fun, plinking, etc.

 

[MK11]

Jeff: Anecdotal stuff on the Internet

 

[Rob96]

Everything I have read indicates you will get the desired performance from a barrel length of 16" minimum.

 

[Blain]

Well, my friend and I stopped back at the shop today. The news of increased terrorist alerts and tensions finally got to him. He knew that he needed the gun ASAP! So we went to the shop and he bought the 14.5" barrel version with the AK muzzle break. In 7 days he will be able to actually take it home (stupid waiting period). He seems to be very excited though, as he should be. I, for one, am very proud of him.


Now all he needs to do is to buy some magazines and ammo. What places do you guys recommend for buying ammo? Who has the best deals and so forth.

 

[Rovert]

Blain, from what I've read on AR15.com, there is nominal difference in performance between the 14.5" with a brake, and the 16" without. Apparently, the 1.5" doesn't do much to help. Granted, this is only anecdotal, but there are upsides to a brake in terms of being able to stabilize for follow-up shots.

Your friend did fine. For more information about the AR, and why it's so popular, check the link below. Granted, it's a tad biased, but it sure does make sense.

http://www.ar15.com/content/docs/idealRifle/

Here's my Bushie M4A3. Can't wait to get a TA31 on the top!

 

[Sleeping Dog]

The shorter barrel will produce just a little less muzzle velocity. Accuracy inside 200 yards will be fine. The advantage (for me) of the longer barrel is the longer sight radius. I think my next upper (the 20" A2 is the only one I have now) will be a 24" with the front sight all the way out at the muzzle, space-gun style. That sight picture should be more like my M1.

Bullet performance doesn't need to be an issue. The military bullets have to conform to international specifications (Geneva convention?). Full-metal jacket, for one. For your enjoyment and protection, you can choose from a bunch of bullets that will expand on impact. In fact, if you're hunting with it, military FMJ bullets are illegal in some (most?) states.

Regards.