The Great Debate: 16" vs 18" vs 20" Barrel Lengths

[panzer0170]

There's some nice bullup stuff in the bolt action game, too. Making guns capable of reaching out LOOOONG distances that are about AR-15 in size, or smaller (assuming standard 20", not SBR or such) Expensive, is the only issue

[currahee]

It's not just weight. Getting out of a vehicle or moving through a building is noticeably harder with a longer barrel. If I was a dedicated infantry rifleman in open terrain I would prefer a 20" AR. If I was a dedicated door kicker I would prefer a 12" AR. Since I don't know what the future holds 14.5-16" seems a good compromise.

[hudson5969]

So, once again, we come full circle to "What do you want to do with it?"

[omnivorous]

Dec 7, 2014 19:49:12 GMT -5 hudson5969 said:

So, once again, we come full circle to "What do you want to do with it?"

Given it'll be my one and only rifle intended to be doing any kind of real fightin' with, it'll be my primary weapon for training, and hopefully not, home defence in the event of a major WROL situation. I've got a bunch of old hunting lever and bolt actions I've inherited, but they are in bad need of cleaning; which I really, really need to do.

[waffenmacht]

Dec 6, 2014 1:42:19 GMT -5 omnivorous said:

I've heard the terminal effect argument, but since I'm not working for the military, I can use hollow point rounds, or at least soft noses; not much to worry about "ice-picking", unless its a really close in shoot. I'm all for getting on the bullpup bandwagon, with a Tavor, but a Tavor is like twice-plus the cost of my AR. The Tavor, I'm strongly debating as my next eventual purchase, as a "truck gun". I live in an area which is a mix of urban and rural, and then urban, and then rural again, terrain types. So, something which will work better across a spectrum of fire lanes is more ideal for me.

waffenmacht, are the reasons the Marines in your group went with the 16" barrels over the 20s they're used to, solely for reduced weight and whatnot?

And Erick, a 5.56 AK is definitely in my future, at some point.

"waffenmacht, are the reasons the Marines in your group went with the 16" barrels over the 20s they're used to, solely for reduced weight and whatnot?"

So I asked 3 Marines this question over the weekend to get an accurate answer.  Here is their response:

Marine #1 (M4 spec rifle) "Lighter, shorter, more compact. That's all"

Marine #2 (M4 Colt Magpul Edition) "A rifle length barrel with a fixed stock will always be the same length. For open range shooting that's not a bad thing...Put that inside close quarters, or in heavy vegetation and it becomes a liability.  M4 gives me configurable options on a stable and accurate platform for a changing mission. I like the options built in without having to invest in multiple weapons."  

Marine #3 (Mk18 10.5")  "I like the A2. But try running an A2 suppressed.  The Mk18 lets me run a suppressor without increasing length over a standard M4.  Plus I have an adjustable stock and the Mk18 works great for confines spaces such as a vehicle, but also performs well out to and just beyond 300 meters. When I was in the Marines (one year in Iraq, one year in Afghanistan) if we had any targets beyond 100 yards we just used the 240 G and Mk19. I never used my A2, I was always on the Mk19".

[panzer0170]

Dec 8, 2014 5:32:27 GMT -5 waffenmacht said:

Dec 6, 2014 1:42:19 GMT -5 omnivorous said:

I've heard the terminal effect argument, but since I'm not working for the military, I can use hollow point rounds, or at least soft noses; not much to worry about "ice-picking", unless its a really close in shoot. I'm all for getting on the bullpup bandwagon, with a Tavor, but a Tavor is like twice-plus the cost of my AR. The Tavor, I'm strongly debating as my next eventual purchase, as a "truck gun". I live in an area which is a mix of urban and rural, and then urban, and then rural again, terrain types. So, something which will work better across a spectrum of fire lanes is more ideal for me.

waffenmacht, are the reasons the Marines in your group went with the 16" barrels over the 20s they're used to, solely for reduced weight and whatnot?

And Erick, a 5.56 AK is definitely in my future, at some point.

"waffenmacht, are the reasons the Marines in your group went with the 16" barrels over the 20s they're used to, solely for reduced weight and whatnot?"

So I asked 3 Marines this question over the weekend to get an accurate answer.  Here is their response:

Marine #1 (M4 spec rifle) "Lighter, shorter, more compact. That's all"

Marine #2 (M4 Colt Magpul Edition) "A rifle length barrel with a fixed stock will always be the same length. For open range shooting that's not a bad thing...Put that inside close quarters, or in heavy vegetation and it becomes a liability.  M4 gives me configurable options on a stable and accurate platform for a changing mission. I like the options built in without having to invest in multiple weapons."  

Marine #3 (Mk18 10.5")  "I like the A2. But try running an A2 suppressed.  The Mk18 lets me run a suppressor without increasing length over a standard M4.  Plus I have an adjustable stock and the Mk18 works great for confines spaces such as a vehicle, but also performs well out to and just beyond 300 meters. When I was in the Marines (one year in Iraq, one year in Afghanistan) if we had any targets beyond 100 yards we just used the 240 G and Mk19. I never used my A2, I was always on the Mk19".

Whilst I totally get all of the above answers, and agree 100%, Marine #3 makes an excellent point for having a longer gun. Because you take away those military toys (Gimpy, GMG...) and you need a weapon with... reach. For those on limited funds, 1 rifle may BE the limit. I think, as with everything, scenario dictates. Personally, given my intended AO, I would want a full length barrel. Yes, you lose something room to room, but I have no intention of clearing rooms, above and beyond getting OUT of dodge. I think this is where my experience with a bullpup makes me happier to accept a longer barrel length - LSW has a 24" barrel and if I remember is basically the same size as an M6, and whilst front heavy because of the bipod and extra metal up there, I really never had any problems with it as far as handling. For me, not having the range is a big no-no. Yes, most modern firefights take place within 1-200m. But that's because it's mostly idiots with no clue. Even the non-prep oriented part of america, in large part, can shoot. Whilst I know IPSC and all the other competitions are NOT by any means combat, if they can shoot, and their gat will reach 300m more than mine, and they're HALFWAY TO SMART, they're going to make sure they have that opportunity. For me, I want to be able to piss someone off at 600m with consistency. With a scope I'd like to be able to hit them at that distance, with SOME consistency.

I seem to recall a video showing a rifle held, and a pistol held, both drawn from the same spot - I think the rifle was a 16" AR and overall space taken up was little different to a pistol held out front. Based on THAT info, unless I HAD to conceal a firearm, or I wanted to store something with more power than a pistol in a real small space, I'd certainly never go down to something like a 10.5"

[hudson5969]

Much the same thoughts for #3.
Not to dis those from a military background, but thinking like you did in the military can be very bad. "We had M4s and never needed a long gun." Ok, now look back on your experience, and what would you have done if all you had was a semiautomatic rifle? No air support, no artillery, no machinegun of any type. At that point a lot of people start arguing for battle rifles, for good reason.

#2 I would just lay down the argument that you're not in the Corps anymore, and you don't have to have an A2 stock on a 20". An A5Vltor stock gives the adjustable stock, and cranked down is only about an inch longer than my Remington 870 with 18.5" barrel, which most people consider a good room-clearing gun (unless you show them the AR is of comparble length, then they argue for a 12" shotgun, but I digress).

I'll give the below because 270fps is the speed at which M193 and M855 reliably fragment. As much as guy talk about using controlled expansion rounds (typically need to be above 2400fps), generally you'll find that they have MAYBE one standard load of that $1+ per round ammo, and the rest is M855 or M193. It is also the most likely "find" when you have to resupply. Keep in mind, this is for actual M193 and M855, not commercial .223, nor Wolf or other labeled M193 or M855 -- they do not cut the cannelure as deep, and you generally will not get the fragmentation you get from the Lake City products.

Distance to 2700 fps with M193:

20" Barrel: 190-200m
16" Barrel: 140-150m
14.5" Barrel: 95-100m
11.5" Barrel: 40-45m

Distance to 2700 fps with M855:

20" Barrel: 140-150m
16" Barrel: 90-95m
14.5" Barrel: 45-50m
11.5" Barrel: 12-15m

So, in short, you lose about 50m of effective range going to a 16" barrel over a 20", and 100m of effective range going to a 14.5"

So it really comes down to what you want to optimize for.
Much as it pains me to say, You really can get most of what you want for urban and rural use by going with a longer barrel bullpup. The question you have to ask is "Am I willing to pay the price to optimize for most conditions, or do I want to save money to optimize for one condition?"

Second question assuming you're saving money: "Am I planning on staying in an urban or suburban AO, and having to do a lot of room clearing, or going rural, where I may encounter longer-range engagements?"

If you are staying urban, then you may consider going all the way to a 14.5" with a pinned flash hider. This gives a barrel length of exactly 16", and non-NFA, whereas a 16" is really a 17-17.5" barrel depending on your flash hider.

If you're planning on heading to the woods immediately, then think about a 20" with the Vltor A5 stock. Collapsed all the way, it's really not that bad indoors.

If you really don't know, and you're in money saving mode, buy a folding stock AK.

[panzer0170]

See, by next step straight after a Tavor would likely be an SLR, because.... Well, they didn't ever hit anything they couldn't make fall that walked on two legs, plates or not. Unless you have all the money in the world plates aren't going to work against a good solid battle rifle, and for that, I like them. The reason they're not my first choice is because they're pig heavy. If I were to buy 3 guns to cover 'everything', it'd be a glock 19 (after using a 17, with suggestions from Diz or Hawkeye saying that they're better insofar as recoil...) a Tavor (18" Barrel & bayonet, because yes, I want one, especially if I'm planning on walking through rooms) and a FAL, all set up pretty to throw lead out to several hundred metres, likely with one of them there fancy drum mags (on the weapon, not for reloads) so I can throw down metal if needs be with what is within the law AND not thousands of dollars a firearm (see: anything capable of going full auto, ever).

All in all, it appears to boil down to; Urban? 16. Rural? 20. Not sure, suburban, travelling, or anything else - 18.

[Hawkeye]

A 16" barrel with a midlength gas system is pretty much the best general purpose option in my book.

If I may offer a suggestion...and its just that, a suggestion. Put bullet velocity at the very bottom of your list of decision making criteria. I am well familiar with M193's fragmention velocity (and M855), and I quit worrying about that a long time ago. So did some folks I know personally who have put those rounds into other humans. For our purposes, the various fragmentation ranges etc, really and truly don't matter. At 500 yards a 55gr M193 bullet is still supersonic even out of a 12.5" barrel. That 55gr bullet, going over 1100 fps, that enters your chest cavity and goes through a lung, heart, liver, spine, etc.... is going to ruin your day. Yes, it may not make you INSTANTLY dead, but you will not be able to continue to send effective fire back my way for very long at all, and your definitely not going to effectively traverse that 500 yards to get closer to me. Now, before anyone gets wrapped up in the numbers, I just picked 500 yrds as an arbitrary number. My point is, a rifle bullet going through your body, in excess of the speed of sound, is not going to be something that one just shakes off and laughs at. So, get the barrel length that works best for you, given your area, plans, and expectations.

[panzer0170]

Question;

Is there any difference if we assume rounds are hitting a plate carrier?

Specifically; Is there the same effect of putting someone out of action?

(I totally get the above, and yes, I agree to an extent. But I've also see blokes who haven't realised they've been shot. Who carried on posing a fucking nasty threat (luckily, they were OURS) till they'd lost enough blood their body went 'nope.' I'm not trying to argue, just... Personal experience says 7.62x39 @ 1-200m (ish, no actual figures, mostly guesswork estimation) to the lung might actually not even get noticed, depending on who you're shooting.

And we're not talking drug addled people here, just well trained blokes on pure adrenaline.

There's also a video, somewhere on the internet, with a nice Chinook pilot who takes a round somewhere to the head, and flies the damned thing back to the airfield.

Point being this; I want to hit EVERYTHING I ever have to face, at the longest distance I can hit it. If nothing else, I want a stable predictable projectile for the biggest distance I can, with reasonable practicality. Ideally I'd like 7.62, but weight and recoil. 5.56 is nice, but I want to be able to REACH with it, even in an urban environment. Especially given how with a US block system it's quite easy to open up in a CITY and fire a mile without hitting something, cause you build those roads so nice and straight.)

Not saying you're wrong, just trying to explain my headspace.

[hudson5969]

Adrenaline does funny things. People can go a long time even with a fairly good hit, as long as it's not a CNS hit.

Hawkeye: I wasn't trying to argue, just better explain why I made the choice I made. I felt some numbers would better explain my position, and that explanation was necessary, because my choice goes against the generally accepted response.

[omnivorous]

Dec 9, 2014 1:14:12 GMT -5 hudson5969 said:

Adrenaline does funny things. People can go a long time even with a fairly good hit, as long as it's not a CNS hit.

Hawkeye: I wasn't trying to argue, just better explain why I made the choice I made. I felt some numbers would better explain my position, and that explanation was necessary, because my choice goes against the generally accepted response.

I don't think you have to worry about going against a groupthink here, given one of the reasons behind this forum is to go against groupthink. Right now, it seems like the 16" with a mid-length gas system, is a jack-of-all-trades, master none; which, for my circumstances, seems to be optimal. If one can get another setup to work for them, then more power too them.

[Hawkeye]

Nah, no worries, and no reason to justify anything. Your money, your reasons, your choice . And yeah, adrenaline is a heck of a drug.... however, it is usually pretty short lived effect wise. Just something to keep in mind.

[eddiewouldclearhot]

I think hawk is right on this one. There is a reason that guys who pull triggers for a living tend to opt for shorter barrels, and its not because it's "cool" its because they work well enough for the situation at hand.

that said, it really is about combined arms. We discovered about a hundred years ago that when you mix capabilities, you get all of the strengths and mitigate most weaknesses. For example, by integrating .308s into your group along with ARs, you get the best of both worlds, local fire superiority and the ability to place effective fire at longer ranges.

That may not be an option for you given your group size. In that event, I think a 16 inch midlength is still a good all around option. Personally, i stick with 14.5 because i intuitively understand the bullet drop on that barrel and at the end of the day, i believe that accuracy is more important than a couple FPS difference in velocity at any given range. I think you'll be fine with a 16 inch and will appreciate the increased handiness of the platform.

[Patriotic Sheepdog]

Dec 9, 2014 9:35:47 GMT -5 Hawkeye said:

Nah, no worries, and no reason to justify anything. Your money, your reasons, your choice . And yeah, adrenaline is a heck of a drug.... however, it is usually pretty short lived effect wise. Just something to keep in mind.

Remember, adrenaline is pumped into the blood stream....hence fight to flight. Adrenaline will increase heart rate, blood pressure, and awareness. When the blood stream plumbing system (pipes-arteries and veins) has a hole in it, the fluid (blood) will start to leak out. With less blood flowing in the once closed plumbing system, less adrenaline and more importantly less oxygen getting to the brain and other organs. No matter how small the leak, if the leak continues, the less adrenaline and oxygen circulating around. Eventually, the brain will start to shut down other organs to keep itself functioning. Wait long enough and the brain will be affected as well. That means less blood flowing, and to keep pressure up the brain will constrict arteries and less oxygen will be delivered to muscles as well. Now if you can stop the flow, things can improve, but if you stop the external flow and the internal flow is still leaking...things will eventually get bad. Depending on the size pipe that has been injured the faster things will go south.

Bottom line, no matter the size of the round or fragment, you rip through an artery in the abdomen or chest, life will get real hard sooner or later.

That, boys and girls, is your anatomy and physiology lesson of the day...class dismissed. lol