5.56 10.5" barrel thoughts for LE work?

[Galbraith]

I'm currently splitting the duties of firearms instructor between several other officers, and the one who spear heads equipment procurement is pushing for converting our 40 AR-15s from 16" barrels to 10.5" barrels. I have generally been happy with running 14.5-16 barrels. From the large pool of knowledge in this forum, I was hoping to hear some opinions on this matter. My primary concerns are ensuring good terminal effects of the ammunition out to 200yrds(we are running Speer 62gr Gold Dots). I also have concerns about reliability and muzzle blast(trying to push for suppressors). Any insight into this equipment decision would be most helpful.

[navyman8903]

Not that you can hear a lot with 16" or 14.5" rifles going off, but a 10.5 is going to be even more oppressive. Additionally the ammo concern is valid, you might have to switch to 77gr, but I know of other departments running SBR's with 62gr ammo. You're not going to get the same ballistics out of the gun that you're getting now obviously, and in LE you're going to be dealing with multiple threat scenarios. Which those rounds have to deal with. Range, clothing, body type, armor possibly....you get the idea. I also think suppressors for those SBR's will be a requirement, but I doubt they'll spring for them. My wife's department authorizes SBR's but the cans are taking forever to get "validated."

[TGS]

I'm currently splitting the duties of firearms instructor between several other officers, and the one who spear heads equipment procurement is pushing for converting our 40 AR-15s from 16" barrels to 10.5" barrels. I have generally been happy with running 14.5-16 barrels. From the large pool of knowledge in this forum, I was hoping to hear some opinions on this matter. My primary concerns are ensuring good terminal effects of the ammunition out to 200yrds(we are running Speer 62gr Gold Dots). I also have concerns about reliability and muzzle blast(trying to push for suppressors). Any insight into this equipment decision would be most helpful.

I think 12.5" is going to be your sweet spot.

The blast is noticeably less than 10.5", the service life is longer, and the velocity increase over a 10.5" is exponential within just those few inches. The 10.5" is useful for niche applications and you can make them reliable these days. We use Daniel Defense Mk18s, and they are awesome to shoot as long as you're wearing double ear-pro. The recoil is amazingly soft, and even against "legacy" Mk18s they are very lightweight and handle like a dream. Shooting next to any sort of barrier feels like getting hit in the face. I don't think they're an ideal weapon for a general patrol rifle, and think 12.5" is a much better option.

The 12.5" mitigates the concussion and will extend the service life of the weapon. However, to your primary concern of terminal effects out to 200 yards, the Speer 62gr Gold Dot is good out to ~200 yards from a 10" barrel. It will expand down to 1800fps or so, IIRC.

ETA: Galbraith,

Where in MO are you located? There's a sergeant at UMKC PD with a sweet 12.5" setup. Gun guy. I'm sure he wouldn't mind talking to you about it or shooting if you reached out to him.

[Mike C]

I'm currently splitting the duties of firearms instructor between several other officers, and the one who spear heads equipment procurement is pushing for converting our 40 AR-15s from 16" barrels to 10.5" barrels. I have generally been happy with running 14.5-16 barrels. From the large pool of knowledge in this forum, I was hoping to hear some opinions on this matter. My primary concerns are ensuring good terminal effects of the ammunition out to 200yrds(we are running Speer 62gr Gold Dots). I also have concerns about reliability and muzzle blast(trying to push for suppressors). Any insight into this equipment decision would be most helpful.

While I am not an expert nor DocGKR I absolutely would not want to run a 10.5" without a suppressor, I say that having shot a lot of 14.5's indoors with and without hear protection while overseas in Iraq. When being in a room with or near AWG and SF folks who where running 10.5's it was deafening. I will leave DocGKR to speak to effectiveness and what what range terminal effects will be adequate for the ammunition you are seeking info on. I will say that he has stated that the 62gr GD was good stuff better still was the 75gr stuff. If you have credentials I'm certain you can call Speer/ATK and get information that would other wise not be published, outside of that I would PM DocGKR directly. He is certainly the person I would seek out. Here is a good thread on the topic in general with some excellent advice on ammunition selection by the good Doc.

https://pistol-forum.com/showthread.php?4344-5-56-mm-Duty-Loads

[rob_s]

I'm pretty out of touch with the AR world these days, but I use to know some stuff, and I'm not in LE but...

Oversimplifying:
I would go 12.5" if unsuppressed, and 10.5" if suppressed, and I'd really only go suppressed these days if it was a dedicated gun/upper. I'd still probably use a brake mount just to help protect the baffles (if that's even still a thing) but I'd work on "tuning" the gas port down (probably with an adjustable gas block) to optimize the use of the suppressor just to keep as much of the backsplatter to a minimum as possible. Even with all of that, I'd want a 7.62 can so as to make it do multi-duty (again, good reason for the brake mount).

[Gray222]

Completely depends on what your mission and AO is.

If you work in an rural department a 16" might be worth the FPS over a 10.5".

If you work in an urban department a 10.5" might be worth the CQB/vehicle movement ability as engagement distances are likely sub 100m.

As TGS said, 12.5 is probably the best of both worlds, but I'd say most departments don't generally care about the individual needs, they just buy whatever is cheapest.

[HCM]

11.5” and 12.5” DI guns are notably more reliable than 10.5” /10.3”.

In addition to the noise and blast issues already noted, the 10.5” gun wear at an accelerated rate vs longer guns.

[HCM]

I'm pretty out of touch with the AR world these days, but I use to know some stuff, and I'm not in LE but...

Oversimplifying:
I would go 12.5" if unsuppressed, and 10.5" if suppressed, and I'd really only go suppressed these days if it was a dedicated gun/upper. I'd still probably use a brake mount just to help protect the baffles (if that's even still a thing) but I'd work on "tuning" the gas port down (probably with an adjustable gas block) to optimize the use of the suppressor just to keep as much of the backsplatter to a minimum as possible. Even with all of that, I'd want a 7.62 can so as to make it do multi-duty (again, good reason for the brake mount).

I would not put adjustable gas blocks on a duty rifle, especially not an issued duty rifle.

[John Hearne]

In a 5.56 gun, I wouldn't go shorter than 11.5" unsuppressed unless it was an honest-to-god Daniel Defense MK18 upper. BCM was pretty adamant about not going below 11.5" for reliability. IIRC, there was a 40% increase in dwell time when you stayed at 11.5" versus 10.5"

[rob_s]

I would not put adjustable gas blocks on a duty rifle, especially not an issued duty rifle.

Yeah I don’t think I would either. I got a bit carried away with the “suppressed” side when what I want to reinforce is that I’d suggest 12.5 for the OP’s situation.

Of course, that’s assuming that they have to do anything at all. It would not surprise me in the least to discover that the office that wants to make the switch is caught up in just wanting short barrels. Particularly if the current barrels aren’t shot out or otherwise unsat other than length (which is also unlikely).

[TGS]

In a 5.56 gun, I wouldn't go shorter than 11.5" unsuppressed unless it was an honest-to-god Daniel Defense MK18 upper.

What's the black magic involved in DD's Mk18?

All I know is that it's svelte to handle, reliable, and shoots as softly as my 14.5" BCM middy.

The time it takes me to get two shots on a 25y steel plate with the legacy Mk18, I can put 5 on target with the Daniel Defense Mk18.

[HCM]

Yeah I don’t think I would either. I got a bit carried away with the “suppressed” side when what I want to reinforce is that I’d suggest 12.5 for the OP’s situation.

Of course, that’s assuming that they have to do anything at all. It would not surprise me in the least to discover that the office that wants to make the switch is caught up in just wanting short barrels. Particularly if the current barrels aren’t shot out or otherwise unsat other than length (which is also unlikely).

Rifles belong up front in LE vehicles. The one instance I’ve found where short barrels are a real advantage is deploying from within or out of vehicles.

Nothing wrong with suppressed guns but on an issued gun, set it up suppressed (reduced gas port) and run it suppressed all the time.

[rob_s]

Rifles belong up front in LE vehicles. The one instance I’ve found where short barrels are a real advantage is deploying from within or out of vehicles.

Nothing wrong with suppressed guns but on an issued gun, set it up suppressed (reduced gas port) and run it suppressed all the time.

can't speak to the former, but agree on the latter.

For an agency, that might be easy-ish to do (although 40 guns/uppers might not be enough to get the attention it would require), but again I may be out of touch with the industry. Getting a particular barrel/suppressor/ammo combo to work together *and* getting people to stick to that combo used to be pretty hard to actually make happen, hence my original threadjack into adjustable gas blocks (and just so we don't have to keep beating on that horse, I'd like to reiterate that I agree with you about not putting them on issued guns).

[Beat Trash]

I'm currently splitting the duties of firearms instructor between several other officers, and the one who spear heads equipment procurement is pushing for converting our 40 AR-15s from 16" barrels to 10.5" barrels. I have generally been happy with running 14.5-16 barrels. From the large pool of knowledge in this forum, I was hoping to hear some opinions on this matter. My primary concerns are ensuring good terminal effects of the ammunition out to 200yrds(we are running Speer 62gr Gold Dots). I also have concerns about reliability and muzzle blast(trying to push for suppressors). Any insight into this equipment decision would be most helpful.

What type of environment does your agency patrol? Urban or rural, or a mix of both? You mention wanting good terminal effects out to 200 yards. For most LE agencies, 200 yards is a long shot. Unless the officer is taking direct fire, identifying and justifying lethal force from 200 yards away could be a challenge. Especially in today's legal environment. In my agency, it's mostly urban to inter-city. The majority of armed threats are well under the 50 yard range, and I'd say mostly under 25 yard range. At these distances, you don't loose much by going to the SBR over the 16" guns.

SBR's are easier to deploy when exiting a vehicle under stress. But when we started switching from the Crown Vic's to Explorers, the larger door of the Explorer makes it easy for me to roll out with my 16" patrol rifle. So it depends on what type of vehicles your agency is fielding, and how much crap is inside of these vehicles, as to how much of a benefit converting to SBR's would add.

If your officers are doing mostly perimeter work with their rifles, the 16" barrels are just fine. If it's more building clearing work, then the SBR may be the way to go.

If you do decide to covert your existing guns, I would use 11.5" barrels instead of the 10.5's. The extra inch is definitely worth it for the almost 40% increase in dwell time and decrease on the wear and tear on the guns. Longer dwell time will increase the reliability of the gun.

There is also the ugly but ever present issue of cost. Do you have the funds in your budget to convert 40 guns? If so, then I'd strongly consider buying 40 11.5" uppers and being done. If money is tight, then you might make a convincing argument that buying new uppers is cheaper than buying new rifles. Or convert a number of guns per year, as budget permits, until your entire inventory is converted. Starting with the oldest guns with the most rounds through the barrels.

[Mike C]

I just wanted to drop some more thoughts. By the time you suppress an 11.5 you're at or near 14.5/16" guns depending on suppressor length so maneuverability is about the same. If your department doesn't get suppressors whether you're going to 10.5-12.5" you're still going to have a flashing attached to the end of your muzzle. You may not get suppressors with the added costs. I'd plan for that since budgets are a thing for most departments. (I'd present both plans, 11.5's with suppressors and 14.5's). If I knew I would get the shorter barrels and suppressor and was in a more urban environment then I'd get the 11.5's and suppressors but if that's not likely I'd go with the 14.5's get better ballistics increased terminal performance at longer ranges and not be blowing everyone's ears out. You'd also be reducing cost and would probably be easier to sell. Also I believe it was Pressburg who mentioned another advantage for the 14.5" is being able to work the barrel out past intermediate barriers like a windshield which makes a lot of sense for LE running one from inside a vehicle, (maybe not highly likely but still possible).

[StraitR]

Another consideration is ammunition. Whatever your current duty ammo choice is for 16" guns, may or may not perform as well out of a 10.3/10.5" barrel. More often than not, ammunition that performs well in 16" guns will over-penetrate out of 10.5" guns.

So if you ended up running both barrel lengths, as many departments do around here (16" for patrol, 10.5" for SWAT), then you will likely end up needing to purchase two kinds of ammunition.

[John Hearne]

What's the black magic involved in DD's Mk18? ... All I know is that it's svelte to handle, reliable, and shoots as softly as my 14.5" BCM middy. ... The time it takes me to get two shots on a 25y steel plate with the legacy Mk18, I can put 5 on target with the Daniel Defense Mk18.

The MK18 is an intentionally designed, vetted, and tested solution for a less than 11.5" gun. It's been a proven over gassed solution that will run at the cost of long term durability. And realistically, it's a 10.8" barrel - that's less than half an inch shorter than an 11.5" upper.

[TGS]

The MK18 is an intentionally designed, vetted, and tested solution for a less than 11.5" gun. It's been a proven over gassed solution that will run at the cost of long term durability. And realistically, it's a 10.8" barrel - that's less than half an inch shorter than an 11.5" upper.

Yeah, I get that.

I was asking what makes the Daniel Defense Mk18 so good compared to other 10.xx" guns. You stated you wouldn't take a 10" gun unless it was a true-to-god Daniel Defense. Why?


Another consideration is ammunition. Whatever your current duty ammo choice is for 16" guns, may or may not perform as well out of a 10.3/10.5" barrel. More often than not, ammunition that performs well in 16" guns will over-penetrate out of 10.5" guns.

So if you ended up running both barrel lengths, as many departments do around here (16" for patrol, 10.5" for SWAT), then you will likely end up needing to purchase two kinds of ammunition.

He already stated Speer Gold Dot 62gr, which is fine out of 10" guns out to ~200 yards.

[StraitR]

He already stated Speer Gold Dot 62gr, which is fine out of 10" guns out to ~200 yards.

I did a poor job of reading his thread, didn't I. Kind of jumped right into the responses.

In that case, I would suggest the OP have their local Speer rep come by and do a demo shoot (all protocols), with multiple (different) lots of 62gr GD to ensure they see what they want to see.

[HCM]

I'm currently splitting the duties of firearms instructor between several other officers, and the one who spear heads equipment procurement is pushing for converting our 40 AR-15s from 16" barrels to 10.5" barrels. I have generally been happy with running 14.5-16 barrels. From the large pool of knowledge in this forum, I was hoping to hear some opinions on this matter. My primary concerns are ensuring good terminal effects of the ammunition out to 200yrds(we are running Speer 62gr Gold Dots). I also have concerns about reliability and muzzle blast(trying to push for suppressors). Any insight into this equipment decision would be most helpful.

One thing to consider is even on agency guns you must do ATF form 5s and add your ARs to the NFA registry to SBR them. This could also be extra work if you wanted to trade or sell them later,

[Mike C]

One thing to consider is even on agency guns you must do ATF form 5s and add your ARs to the NFA registry to SBR them. This could also be extra work if you wanted to trade or sell them later,

You are a wealth of knowledge and I appreciate how much of it gets shared here. Thank you.

[HCM]

You are a wealth of knowledge and I appreciate how much of it gets shared here. Thank you.

You’re welcome. Form 5 is a tax free transfer but agency owned stuff is still subject to NFA. Along those lines, local agencies here have had to wait several months for form 5 approval on agency suppressor purchased.

[bravo7]

There are agencies that run 10.5s suppressed/unsupressed just fine with 62gr.

[TGS]

There are agencies that run 10.5s suppressed/unsupressed just fine with 62gr.

It's true. We do, and I love our Daniel Defense Mk18s. Even our legacy CQBR uppers are "okay" (though they definitely don't shoot as nicely). The DDs are a hoot. The service life is short, but they've been perfectly reliable for me with XM556FBI3T ammo.

With that said, there's really no reason to take one over an 11.5", even if concealing them and working in extremely close confines is the name of the game. The 11.5" offers objective benefits over the 10" guns, and the average police officer is not in situations where that short of a rifle is actually of benefit (unless running a can). The 12.5" is an even better match, given it retains 90% of the velocity of a 20" barrel and the concussion is more akin to a 14.5" than it is the 10" or 11" guns...yet still gives you a very short carbine to maneuver inside buildings or deploy from a vehicle with.

It's the ideal GP carbine length unless you're in the business of mounting underslung grenade launchers or bayonets (literally the reason the 14.5" exists).

[Casual Friday]

I won't try to speak on the LE side of the question, but 10.whatever" guns make everything harder than it has to be. The guns run harder, you have to work harder. The window is smaller for reliability and smooth cycling. They're either running smooth or beating themselves to death.

Step up to a 11.5" and life gets way easier. In fact, I'm not sure there is any other 1" change in barrel length for the AR15 that will have the kind of immediate appreciable difference that jumping from 10.5-11.5" will have. My Colt 6933 uppers and my BCM 11.5" ELW will run a wide variety of ammo, from Wolf to full power 5.56 loads without feeling like they're over or under gassed. They run so well and are such a pleasure to shoot that I find myself not shooting my 16" gun, like ever.

That said, the newer MK18 uppers with the crane spec .070" gas port have a much more smooth and proper feeling cycle, but you still know you're rocking a 10" gun. If I had a specific need to go under 11.5" I'd go with a new MK18.

[Wake27]

Also I believe it was Pressburg who mentioned another advantage for the 14.5" is being able to work the barrel out past intermediate barriers like a windshield which makes a lot of sense for LE running one from inside a vehicle, (maybe not highly likely but still possible).

Not sure if we’re thinking of the same thing, but I remember him saying something similar though it wasn’t in regards to barrel length - it was about handguard length. He was making a point for shorter handguards by saying that it’s far easier to punch just the muzzle and barrel through a windshield than it is a muzzle with a flashlight and fat handguard right behind it. Again, not sure if it’s the same reference or not.


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[DocGKR]

Lot's of good advice above.

At this point in time I still strongly prefer a 5.56mm AR15 16" mid-length barrel with long FF rail for general purpose use or a 11.5-12.5" barrel with a dedicated suppressor.

If you are with a USG LE agency, then use the excellent Federal 62 gr TBBC load off the FBI contract. With a municipal, county, or state LE agency then the 62 or 75 gr Gold Dot are usually much more affordable and work adequately. TSX and GMX are also acceptable options.

[rob_s]

Not sure if we’re thinking of the same thing, but I remember him saying something similar though it wasn’t in regards to barrel length - it was about handguard length. He was making a point for shorter handguards by saying that it’s far easier to punch just the muzzle and barrel through a windshield than it is a muzzle with a flashlight and fat handguard right behind it. Again, not sure if it’s the same reference or not.

this may be a "gamer" or training thing, but your post made me think of running the 9-hole wall with a friend. He had a 16" barrel with a 15" handguard, and I had a 16" barrel with a ~10" handguard. he had a much harder time "finding the hole" than I did. I realize there's a lot of folks that would say to never poke the barrel beyond "cover", and again I'm not a cop so I can't say how often that might happen in that line of work, but it's definitely a thing (just not sure if it's a thing that matters to anyone).

[Mike C]

Not sure if we’re thinking of the same thing, but I remember him saying something similar though it wasn’t in regards to barrel length - it was about handguard length. He was making a point for shorter handguards by saying that it’s far easier to punch just the muzzle and barrel through a windshield than it is a muzzle with a flashlight and fat handguard right behind it. Again, not sure if it’s the same reference or not.


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It was in regards to his preferences for a GP carbine, barrel length, ballistics capability and hand guard length if I remember correctly. In order to have adequate handguard length on a SBR like 10.5 you need as much handguard as you can get making it impossible to jam the muzzle past a windshield due to rake unless there is a suppressor attached to the end of it and f#$% firing a 10.5" from inside a car with no suppressor.

[El Cid]

Put me in the 11.5” camp. Even with a vetted manufacturer, I see no reason or benefit to go shorter than 11.5 with 5.56 rifles. The drawbacks already mentioned in this thread and others are not worth it for a rifle that’s an inch shorter in my opinion.

[DocGKR]

Agree.

[Casual Friday]

Not sure if we’re thinking of the same thing, but I remember him saying something similar though it wasn’t in regards to barrel length - it was about handguard length. He was making a point for shorter handguards by saying that it’s far easier to punch just the muzzle and barrel through a windshield than it is a muzzle with a flashlight and fat handguard right behind it. Again, not sure if it’s the same reference or not.


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That's the one I'm thinking of.


this may be a "gamer" or training thing, but your post made me think of running the 9-hole wall with a friend. He had a 16" barrel with a 15" handguard, and I had a 16" barrel with a ~10" handguard. he had a much harder time "finding the hole" than I did. I realize there's a lot of folks that would say to never poke the barrel beyond "cover", and again I'm not a cop so I can't say how often that might happen in that line of work, but it's definitely a thing (just not sure if it's a thing that matters to anyone).

Running drills on a VTAC barricade caused me to dump a 15" handguard in favor of a 13".

[Wake27]

That's the one I'm thinking of.



Running drills on a VTAC barricade caused me to dump a 15" handguard in favor of a 13".

I can see that to an extent, but as long as I can get the muzzle through, I don’t think that it’s worth the other drawbacks. That’s part of the reason my light is just behind the muzzle. At my first class, I was missing a piece of steel like crazy when supported off a barricade. I knew better than to put the barrel on the barricade but had done so anyways since I was most concerned about making hits and the timer than careful placement of the support. Ever since, I’ve strongly preferred fully extended handguards. For me, barrel protection is number one, followed by support hand placement and mounting options. Being able to poke through small holes is far less of a concern, and as I said, as long as the muzzle is clear, that’s all I can think of really needing.


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[rob_s]

At my first class, I was missing a piece of steel like crazy when supported off a barricade. I knew better than to put the barrel on the barricade but had done so anyways since I was most concerned about making hits and the timer than careful placement of the support.

At what distance were you shooting and missing?

IMO 16" barrel and 13" handguard is about the perfect balance of barrel coverage/exposure.

[Wake27]

At what distance were you shooting and missing?

IMO 16" barrel and 13" handguard is about the perfect balance of barrel coverage/exposure.

I think it was somewhere between 30-50 meters, but it was several years ago so I really don’t know. Couldn’t tell you the size of the plate either, all I know is that it should’ve been an easy shot. I threw probably around eight or so before looking at the instructor and asking what I was doing wrong. He told me to look at my barrel, I felt like an idiot, fixed it, and the next shot was a hit. Also, I just think that full length handguards look better.


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