How does Law Enforcement manage to get by with M&P15s?

[pinzgauer]

I thought the RE failures were largely due to the thread cut method on commercial "tubes"... not so much the material.

That could very well be, though I believe they've also occurred on military carbines. Private snuffy, etc.

I would never consider busting steel packing crate bands by using my pencil barrel as a pry bar.

But that apparently happened, enough that that was some of the justification for the A2 profile.Though it's well known that the marksmanship teams also had a big hand in that.

[lysander]

Did you know that the Army serious looked at, and tested plastic for the charging handles? They found they were strong enough (no failures in field tests at Ft Benning), but the 1960s plastic got brittle at low temperatures. 6061 has a lot higher yield strength than plastic.

As to some of the other things:

- An officer without communication is in a far worse place than an officer with a broken rifle.

- There is a huge difference between "as good as" and "good enough".

- Who the manufacturer is makes a big difference/

- I have no vested interest in S&W, Colt, or any other manufacturer.

- 6061 aluminum is not as bad as people seem to think. Every optic body I know of is made from 6061, or cast aluminum like A357, which is not as tough as 6061. 6061 has a strength equal to the steel used in building and bridges.

I am I saying that an S&W is as good as a Colt or other "well regarded" brand? No, of course not. I have held an M&P15, and yeah they aren't as pretty and their spec-sheet shows that they are made with maximum economy in mind. But, that is very different from saying it is not reliable enough for patrol use.

[pinzgauer]

Did you know that the Army serious looked at, and tested plastic for the charging handles? They found they were strong enough (no failures in field tests at Ft Benning), but the 1960s plastic got brittle at low temperatures. 6061 has a lot higher yield strength than plastic.

I have seen and handled some 6-7th generation plastic lowers of a specific type that use steel in key places to deal with the high stress areas that are surprisingly durable. We know outside of a couple of areas the lower is not a highly stressed part, but it's still surprising how well they are holding up.

- An officer without communication is in a far worse place than an officer with a broken rifle.

This is an area that I am expert regarding qualitative and operational differences. Simply put, a mil mfg decided to move into the pub service communications space. I actually like the company, they make good mil equipment. But they are 2-3X the cost of the incumbent (Motorola) for the same functionality pub service radios, and if anything have an unproven track record for that market segment. They sold, and agencies bought, a gold plated" standard which was used to make it a sole source procurement. To be very clear, Moto (warts and all) is not at a reliability / operational disadvantage in this space.

If anything, this is like your 7075 mag button issue. Over specification/gold plated specs.

But the core point: LEO locally is spending 10-20X what were are talking about for carbines, and that's just the officer part. They are spending like drunken sailors.

- There is a huge difference between "as good as" and "good enough".

I'm very clear on the difference. And you have been making "it's good enough, it won't hardly be used" argument all along.

To me, that's a slippery slope. I have a son and son-in-law in combat arms positions in the Army. One Infantry, one Artillery in an IN unit. One currently deployed in a hot area. I want them to have the best equipment where it matters. At the same time I recognize they are subject to "lowest bidder" gov procurement stuff.

I never bought into the "all you need is a 6920 and a G19, anything else and you are a gun fud" fad when it was the rage on M4C. I think there is room for multiple mfg's.

That said, my observation is that there are some sweet spots (quality+functionality/$) that are truisms. Colt vintage 6920 OEMs being a prime example. And I would not have put most SW & FN commercial offerings in that bucket. Do I (personally) need 4150CMV/7075, etc? Clearly not. Especially not if it was double the cost. But if I can get it for close to the same cost, yeah I'll take it.

From current reports, it's not clear to me if Colt is still making things the same. So the old adage may be out of date anyway. IG is long gone (RIP), the chart is dead, and Colt is not the same. Even DD & FN uses 6061 RE's, etc. So you raise some fair points on the alloy stuff even if it would not be my pick. Good enough may well be good enough!

[1168]

That could very well be, though I believe they've also occurred on military carbines. Private snuffy, etc.

I would never consider busting steel packing crate bands by using my pencil barrel as a pry bar.

But that apparently happened, enough that that was some of the justification for the A2 profile.Though it's well known that the marksmanship teams also had a big hand in that.

Military rifles are expected to be able to physically beat the shit out of someone until they are neutralized, and still function as a reliable firearm afterwards. I’d bet that a DS/DI could comment on how well M4s respond to that. I’ve personally never seen a military RE get broken except in cases where the user was killed or incapacitated in the event, that I can remember. Either way, that’s not really a requirement for cops. I’d agree that cutting corners there makes me suspicious of cut corners (extractor springs) elsewhere. Not necessarily talking about SW with that.

Motorollas do work just fine for cops, too.

- 6061 aluminum is not as bad as people seem to think. Every optic body I know of is made from 6061, or cast aluminum like A357, which is not as tough as 6061. 6061 has a strength equal to the steel used in building and bridges.

There are a few optics made of (forged) 7075, including ones in use by the US DoD, and probably some cops. Why? I dunno. I defer to the engineers on that one, because they are in fact extremely durable, and I don’t know shit else about that topic.

This thread is a spinoff from one by a dude asking about a rifle to shoot 700+ yards with at unspecified target types, and essentially is a retort to the advice given there, by another dude. There’s good info in here, but that context is key to understanding how this discussion started in the first place. I don’t think anyone here that says “get a 6920 and move on” ever said that a (quality) M&P will get you kilt in da streetz. A M&P9/G19/APX and whatever AR that can reliably survive training and quals for a few years and a few bumps and bruises, and hit a B/C/-1 zone 20 times at 100yds is fine for much of LE. A .mil user or an enthusiast might have other needs/desires. Some LEOs will also have more specific and/or stringent requirements.

[lysander]

And you have been making "it's good enough, it won't hardly be used" argument all along.

I have not said ". . . it won't be hardly used . . ."

I have consistently stated an expected life of 6,000 rounds, and should be reliable for that period.

What I have been getting at, and it seems to be missed, is it will not be used in the manner in which military carbines are used, and therefore many of the durability issues the military specifications are meant to address are not relevant. Further, durability and reliability are two different things. One can design a car that will start up every time you turn the key and take you anywhere you want for 100,000 miles, then die and not work ever again. Also, one can design a car that will last 500,000 miles, but every week you will be out under the hood adjusting something.

I would never consider busting steel packing crate bands by using my pencil barrel as a pry bar.

But that apparently happened, enough that that was some of the justification for the A2 profile.Though it's well known that the marksmanship teams also had a big hand in that

That was proven to be a myth, bending barrels trying to open boxes. And no engineers tried to use that as a justification for the A2 barrel profile. If they had been asked, they would have noted that an M16A1 barrel is just as stiff and unbendable as an M14 barrel.

. . . "lowest bidder" gov procurement stuff. . . "

"Lowest bidder that can meet the requirements."

Or, do you think it would be a better idea to buy from the highest bidder?

[SteyrAUG]

That could very well be, though I believe they've also occurred on military carbines. Private snuffy, etc.

I would never consider busting steel packing crate bands by using my pencil barrel as a pry bar.

But that apparently happened, enough that that was some of the justification for the A2 profile.Though it's well known that the marksmanship teams also had a big hand in that.

In any drop test, military AR carbines almost always fail at the buffer tube. It has been explained to me that mil spec are stronger than commercial, but that is still the fail point for most impact damage.

As for A2s, I never completely understood how that protected the barrel from getting bent when using as a pry bar, wouldn't it just bend behind the FSB? It's not like the handguards are providing some kind of structural integrity. I really do think it was just a matter of a "heavy profile" (even if just in front of the FSB) to stiffen the barrel and provide better accuracy, especially for M4s.

[Echo40]

4140 barrel steel, 1/9 twist. So even the high end S&W at $1400 isn't up to the same spec as a $800 6920

Supposedly the brunt of the cost comes from the Troy Flip Up Battle Sight and Quad-Rail, which is completely absurd, if you ask me, but then again, I bought it for $546 as a police trade-in, so I paid a mere fraction of the MSRP for a gun with nothing more than light external wear, inside it was literally Like New, probably spent most of its life in a Cruiser.

Don't ask me why S&W didn't spring for a 4150CMV 1/7 Barrel, especially when they were using them for other models. Either way, police bought them, and they remain in their LE Catalog to this very day, so evidently they're popular with police.

I'm guessing that police are of similar mindset to lysander, that the materials are sufficient for the task and S&W offers them some outstanding deals on purchasing a bundle of M&P9 Pistols with M&P15 Rifles which presumably places them beneath the cost of Colt.

[lysander]

In any drop test, military AR carbines almost always fail at the buffer tube. It has been explained to me that mil spec are stronger than commercial, but that is still the fail point for most impact damage.

As for A2s, I never completely understood how that protected the barrel from getting bent when using as a pry bar, wouldn't it just bend behind the FSB? It's not like the handguards are providing some kind of structural integrity. I really do think it was just a matter of a "heavy profile" (even if just in front of the FSB) to stiffen the barrel and provide better accuracy, especially for M4s.

The fat part ahead of the front sight does nothing to prevent bending. If an A2 barrel is used as a pry-bar it will bend where the moment is highest, at the root just ahead of the chamber swell. According to an engineer from Picatinny the M16 had a reputation as having a flimsy barrel and they wanted to make it "look more substantial."

As to drop tests, all of the reports I have read say nothing of the extension failing.

"XM4 Carbine Development Program," Taylor, J. & Waterman, H., Colt Industries for ARDEC, Sept 1987.

"Tests conducted on the plastic sliding buttstock indicate that this design, similar to the M16A2 rifle buttstock, protects the aluminum receiver by superior shock absorption to the previous material [lysander - the aluminum buttstock of the XM177A2]. In the test, wherein the carbine is pivoted from the barrel muzzle and strikes a concrete floor on the toe or heel of the buttstock, the lower receiver ring (which accepts the extension) is much better protected by the buttstock made of 80G33 material due to these shock absorption properties. [lysander - The M16 had a tendency to crack the lower receiver ring, aka the horn. This area had been beefed up at least four times* over the life of the M16/M4)

"In the vertical test (eight feet drop on concrete) with the buttstock extended, the plastic stock may crack through the hub for the lock pin. This breakage, however, does not prevent buttstock movement through its dual position. The carbine may be shoulder fired in this cracked condition without a detrimental effect as stock position is not lost. Often when the aluminum buttstock is subjected to the vertical drop, the lock pin jams shear material, and freezes partially retracted."

"Abbreviated Report for the Initial Production Test (IPT) of the Carbine System, 5.56mm, M4." Hubbard, L., U.S. Army Aberdeen Test Center, APG, MD, Oct 1996

"2.8.3 Test Procedures

"a. Testing was performed in accordance with TOP 3-2-045. . . .

"b. The weapons were dropped from a height of 5 feet above a flat concrete floor in the following attitudes (rear sight elevation knob set on the 6/3 mark for 300 meters).

"(1) Top side edge of rear sight impacting (rifle 135° from normal).

"(2) Top edge of stock impacting on cinder block edge.

"(3) Side of stock impacting on cinder block edge.

"(4) Side of handguard impacting on cinder block edge.

"(5) Bottom of handguard impacting on cinder block edge.

"(6) Top of carrying handle impacting on cinder block edge.

"(7) Side of carrying handle impacting on cinder block edge (rifle 135° from normal).

"2.8.4 Test Findings

"a. Some damage occurred to the rear sight, stock, and carrying handle. The damage was not severe enough to cause any type of safety-related problems. Minor abrasions and scratches were apparent on all carbines.

"b. The carbines fired without incident before and after the Rough Handling test. No stoppages/malfunctions occurred before or after the test.

"2.8.5 Technical Analysis

"The carbines completed the Rough Handling test adequately and without incident. No incidents occurred which contributed to degradation in the system. . . ."

If you have other reports that show different results, I would be happy to read them.

_ _ _ _ _ _ _ _ _ _ _ _
* 1) Removal of the cross pin and its hole for the receiver extension around 1969
2) Adding a rib, increasing the width of the horn to 1.520" in 1971
3) Thickening the base where it blends into the .89" width in 1992 or 1993.
4) and thickened it some more again in 2004.

[SteyrAUG]

The fat part ahead of the front sight does nothing to prevent bending. If an A2 barrel is used as a pry-bar it will bend where the moment is highest, at the root just ahead of the chamber swell. According to an engineer from Picatinny the M16 had a reputation as having a flimsy barrel and they wanted to make it "look more substantial."

As to drop tests, all of the reports I have read say nothing of the extension failing.

Regarding the A2 barrel doing nothing to prevent bending, I think I said essentially the same thing.

As for drop tests, I'm referring to drop tests of CAR-15 rifles vs. other rifles done in the 70s. When an AR carbine eventually breaks, that is where the break will happen.

[shadowspirit]

...From current reports, it's not clear to me if Colt is still making things the same. So the old adage may be out of date anyway. IG is long gone (RIP), the chart is dead, and Colt is not the same. Even DD & FN uses 6061 RE's, etc. So you raise some fair points on the alloy stuff even if it would not be my pick. Good enough may well be good enough!

This is a subject for a different thread but many are curious if Colts currently made are as good as ones in the past. Some things are different like more outsourcing if I'm not mistaken but no one has any concrete knowledge or evidence whether Colt quality has gone down.