And yet 40 years later the AR15(M16/M4) is one of, if not the best firearm platform to have ever existed. It is really interesting to see to follow the sorted past of such a successful firearm.
That's not to say it's not a good rifle though, but I don't think that in a military context it's fundamentally better or worse than any of its peers, such as the H&K G36, the Steyr AUG, or the SA80.
At least in the US and Canada, the primary driver is cost. The AR-15 is extremely cheap to make because the receiver is not a pressure-bearing component, and because you need very few machines to make the most important parts (of which there are fewer than most other guns due to the design).
It doesn't help that import restrictions in the US make everything that's not an AR artificially expensive (complying with them has parts/labor overhead if it's even possible in the first place).
The other guns you mentioned are not only more expensive to produce, but they also perform much worse (the SA80 had problems with literally every single part breaking or warping, the G36 melts because its barrel is cast into plastic, the AUG fires when it shouldn't and doesn't handle as well as an AR) to the point where nearly every country that currently uses these weapons are replacing them with some variety of AR15. The original design (gas piston behind bolt = no rotational forces against the carrier = no reinforcement needed in receiver) really is that good.
At which point is one weapon merely a variant of another? Isn't this change in the action a significant improvement?
[1] https://en.wikipedia.org/wiki/M27_Infantry_Automatic_Rifle
The "direct impingement" system of the M16 / AR15 isn't really true direct impingement, as the bolt itself works as a gas piston within the bolt carrier. But the gas has to travel much further to reach it than with a conventional piston.
In fact, many such piston AR retrofits exist in the US civilian AR market, but they’re generally thought to be of “unproven” longevity, at least.
The advantages of the retrofit piston being slim and light is that the recoil increase is small. The disadvantage is that durability is questionable, as those pistons experience a lot of violent force and most guns designed from scratch to be piston operated have significantly heavier duty pistons, for good reason.
You can read online of Marine armorers lamenting how their M27s are breaking down at a rate much faster than their M4s. This is of course anecdotal, but it is also not entirely worthless data.
Or the FAMAS (or maybe it's just my Gallic pride talking ;))
The AR 15 platform has benefited hugely from a lot of refinement and investment over a very long time. That's certainly true, but Stoner's concept for it is just really, really good and the fact that the design issues were all tractable and the further refinements have been largely successful is testament to that fundamental soundness.
It’s beyond fair to lump them into the same thing. And GP is right, there is currently no overall better personal defensive weapon in the world than the AR15/M16.
The 3 differences the article lists between the AR-15 and the M-16 are:
1. The M-16 added a useless "manual bolt closure" making it a bit heavier.
2. The M-16 rate of twist was changed from one-in-14-inches to one-in-12, which made it 40% less lethal.
3. The M-16 switched from IMR 4475 powder to ball powder, which made it much much less reliable. After tons of US soldiers died due to the unreliability, they modified the ball powder and changed the mechanical "buffer" of the rifle, which made it more reliable, but still less than the AR-15.
The Armalite AR-15, the Colt AR-15, the Colt M4, Colt M4A1, FN M4A1, and the military M16, M16A1, M16A2, are all the same weapon with minor modifications. The significant differences are barrel length (interchangeable among most if not all), upper (slick side or with forward assist, not consistent among any of them), buffer weight (generally the full-auto versions have a heavier buffer), trigger model (full auto, 3rd burst, and semi-only -- many variants exist and are interchangeable among most models w/ exception that the civilian models do not have the upper hole that allows for the full-auto trigger components to be installed).
The increase in twist was because the rifle failed to stabilize bullets in some environments during testing, which is a pretty gross defect. And higher twist rates don't decrease lethality, it is actually the opposite for well-understood reasons. Current barrels are 1-in-9 IIRC.
The switch to ball powder happened after the initial usage of the M-16, which is correctly characterized as a logistical screwup, and they ended up redesigning the rifle so that it would perform correctly with the ball powder.
As the Russians seem to be moving to 5.56 the American military is looking to move to the 6mm class.
I hate the forward assist, but not enough to delete it. I mostly use an X95 SBR (13") now, though.
What are they?
The rate of twist varies to stabilize whatever round is most commonly used. 1-7 and 1-9 are commonly used today due to bullet weight.
Powder was an issue in the original issue Vietnam era M16.
In general it is a bold statement to claim something to be the best with so many new options out there.
Most still do, but that is just inertia that is slowly dying out, it is not uncommon for civilian AR rifles to not include a forward assist, i.e. manual bolt closure. I don't keep up with military rifle configs to know if they still continue with forward assists.
>...like the original rifling etc as indicated in the article?
There is quite a lot of variety in barrel rifling these days, 1-in-7 isn't uncommon today and with the variety of rounds available, i.e. heavy bullets/light powder(slow) and light bullets/high powder(fast), barrel twist is also highly variable depending on what works best for your barrel length and cartridge selection.
Overall the AR platform has moved far beyond Stoner's original design, from the Marines recently adopting a "light machine gun" version of it, to the very short length M4s that is the standard today for the US military. Add into that the huge variety of uses and configurations that civilians use the rifle can wear so many hats. There is actually a really interesting series if you're interested from InRange TV, a firearm YouTube channel, that takes a look at what the AR15 might look like if designed with today's material advancements: https://www.youtube.com/watch?v=vI5NPiicXjE
Civilian ones have a lot more variety. For example, with rifling twist rate, it can vary from as slow as 1:16 to as fast as 1:6, depending on whether the rifle is intended to shoot very light and very fast bullets used to hunt small game, or heavier and longer match bullets used by precision shooters.
Military versions all have 1:7 twist (necessary to stabilize long-burning tracer rounds that were adopted as NATO standard, because they're longer). They do retain the bolt forward assist design, but anecdotally I've heard from some people who have actually used them in combat, so perhaps it's not as useless after all.
The only thing I can think of that was reverted to the original design is the fire control selector, which is not discussed in the article. It was originally safe/semi/full, but M16A2 replaced full auto with 3-round burst. It's generally considered a failed experiment, and M4A1 walked it back to full auto.
Unless you can manage to keep it super clean and perfectly lubricated (which kind of counteract each other) you'll be using the forward assist now and again.
There's also a difference between perfectly clean and having used it a while where carbon builds up making it more reliable -- a lot less likely to need it after the third time through a live-fire exercise than pulling it out of the weapons room and heading down to the range.
> It was originally safe/semi/full, but M16A2 replaced full auto with 3-round burst. It's generally considered a failed experiment, and M4A1 walked it back to full auto.
We'd get yelled at if they caught us using 3-round burst because it was a waste of bullets. Each squad had 2 SAWs and each platoon had 2 M60s so they wanted the riflemen to try for precision fire (as opposed to "spray and pray").
I've spent too much of my life with an M16 it seems...
From what I heard, this even affected semi-auto accuracy, because the trigger pull would vary a little bit in different stages of the cycle, making it harder to get that perfect break. Do you recall anything like that from your personal experience?
Hello 2008, my old friend.
I’ve done high speed and thermal camera testing on AR firearms. There is no honest advantage of what you are calling piston guns over DI, which is a short piston on the carrier itself. There are good and bad examples of both, piston AR pattern guns have carrier tilt, extra weight, more parts, more required maintenance, and get just as dirty esp when suppressed as DI guns.
It’s an old opinion you have there. I lived through piston-mania 2008. DI effectively won when you look at anything remotely considering retrofit designs.
Not using a piston has two advantages. First, it's lighter in general, and in particular, there's less reciprocating mass, which means that weapon is easier to control, especially in full auto. Second, the recoil impulse in Stoner's design goes directly back along the bore axis (which is why it doesn't have carrier tilt!), whereas pistons add an angular component, which translates to more muzzle flip.
The disadvantage is that you get carbon deposits in the action. But the effect is usually overstated - there were numerous tests with uncleaned ARs firing several thousand rounds without any ill effects from the carbon - it just keeps running so long as you keep lubricating it. According to Armalite, most of the deposits are in places where they don't matter, and where they do matter, the action itself is designed to remove much of them as it cycles.
So these experiments show that carbon accumulation is not the issue. There are other things about AR design that make it less reliable in some cases (and more reliable in others, like that infamous mud test), but they apply to both DI and piston ARs.
The AR-15 is a piston gun, though: the piston is the bolt itself (the bolt carrier acts as its cylinder walls- this is the reason why the back of the bolt has piston rings). And because said piston is right in the center of the moving parts, you don't have to worry about those parts rotating off their axis (i.e. there's no force tilting them up or down)- the only reason the receiver needs to be there is to hold the barrel on.
This doesn't work for barrel lengths below about 10.5"; at that point an external piston system is indeed more reliable. Also, because the gas tube is a weak point in terms of heat dissipation, the internal piston AR isn't the best choice for sustained automatic fire- but in that case you just give one squad member an external piston gun much like how the Russians distributed their beefed-up AKs.
The latest wars in Afghanistan/Iraq have had no shortage of similar stories of weapons jamming, failing to finre, and malfunctionibng because they were full of sand etc
An in case of the AR family, this is further exacerbated by its modular nature, and the desire to preserve the now de facto standard interfaces between components when updating them individually (software engineers should find this part very familiar...).
You also added
> ..., if not the best
Personally I don't care, I just wanted to point out why people may start arguing : )
Modern variants of Stoner’s design happen to be the lightest weight, smoothest recoiling, most accurate (by a factor of 2-10x), most upgradeable and customizable, and arguably most ergonomic rifles in the the world right now — with no exceptions that I know of. (Incidentally, this is why the AR15 is the single most popular owned firearm in America.) Please feel free to provide any counterexamples in these categories; I don’t really know of any, and I’ve studied this quite a bit.
Most of its excellent performance is due to the direct impingement operating system, which as others have described keep the recoiling mass inline with the barrel (which means the recoil is pretty much entirely linear without any torque, which is virtually impossible to achieve with durable piston designs).
This unique gas operating system design also minimizes the overall weight, because the DI’s compact design eliminates the need for a separate piston / op rod assembly (which in piston operated military designs, must be fairly heavy duty, or else they will break rather rapidly from the violent forces involved). Some say it also explains the extremely high accuracy of the design, by avoiding a heavy reciprocating mass from moving alongside the barrel with each shot, as in a gas piston design.
Thus, this inherently light weight design permits you to choose either (1) a lightweight barrel yielding an overall weight significantly less than any of its competitors, or (2) use heavier and longer barrel which, despite yielding an overall weight matching the “lightweight” version of competitors, far, far exceeds their accuracy capabilities.
It really is a remarkably well engineered system, when you realize that most of the early reliability issues were due to feeding it the wrong ammo (which it was not designed for) and other easily avoidable embarrassing mistakes of mismanagement.
The only real disadvantage again comes from the direct impingement system, which causes the operating mechanism to get dirty and fouled up with burnt powder residue really really fast, whereas gas piston designs (used by virtually all other guns) pretty much stay clean and smoothly running even if you abuse them by never cleaning or maintaining them. There is something to be said for that, especially for military purposes: that is for example one reason why the AK was so successful; it just works. You can and should maintain it, yet if you don’t, it will still work reliably.
So this is just about the only area in which other guns beat out the M16/M4/AR15; while it’s reliability is pretty much on par with any competitor, this remains true only as long as it’s kept cleaned and oiled etc. fairly regularly, especially if it’s used in dirt dusty environments.
That said, the difference may not be as extreme as pop culture makes it out to be: A quality built M16/M4/AR15 will keep functioning for probably at least 5k rounds without any cleaning, before it starts jamming, and some extremely high quality civilian models have been known to go far longer than this in extreme “torture tests”.
It's stuff like e.g. the interface between the receiver and the buffer tube, which is weak and known to break under stress. Or the telescoping stock design, which has a similar problem with the retaining pin - which is why they tell you to never mortar it unless fully collapsed.
There are some issues with the bolt longevity - in an AR, the bolt eventually fails with sheared locking lugs - which is unheard of in AK and not common in other designs. Part of it is due to asymmetric distribution of forces, because of the extractor taking the place of one lug. Modern bolt redesigns try to mitigate this in various ways.
Then there's the enclosed magwell, which is great for quick mag changes, but requires the upper part of the magazine to be straight - which caused troubles for 30-round AR mags historically, until the modern polymer magazine design with internal constant curvature made possible by the manufacturing process. In addition, the magwell is prone to dirt-induced malfunctions - once you get the dirt in, e.g. from the lips of a magazine that fell to the ground, it stays inside, and can block the mag from going all the way in easily. Ice can cause similar issues. The button magazine release can get stuck relatively easily as well. AK well-less paddle system, while slower, is less susceptible to dirt, and the rocking insertion motion and the paddle magazine release provide more leverage even if there is an obstruction.
Or we could look at the antiquated handguard design, which results in precious little rail space on the upper receiver, because the top rail on the handguard, even free-floated, is not as stable (and hence not used for magnifying optics usually, but red dots, lasers etc). Notice how the latest trends in military ARs have been monolithic upper receivers, like in New Zealand's MARS-L, or Canadian MMR?
Of course, you could easily make a rifle based on the Stoner action that has none of these problems - there are more exotic AR variants and accessories that solve one or the other, you'd just need to combine all those solutions. But I don't think it would count as an AR at that point. Even the monolithic upper is already a major difference that breaks compatibility in so many ways. I mean, we don't say that SIG 550 is an AK variant, even though it's also long stroke piston, and the BCG looks very similar to AK. There's more to a gun than its action.
The KAC SR15 solves the bolt longevity issues, but now it’s bolt and barrel extension interface are not compatible with standard bolts.
The LMT MRP platform solves most of the other problems, but not as much the bolt issues. But similarly, the LMT MRP monolithic upper cannot be compatible with standard rails, because that’s exactly the point: to move way from the old brittle way of connecting the hand guard to the upper receiver.
KAC SR15 will last upwards of 50,000 rounds without needing replacement parts, but externally it’s no more physically durable than a standard AR.
LMT MRP is among the most solid and sturdy AR out there, with virtually no way you’re going to break it if you throw it around, drop it, and otherwise abuse it. But internally, it will only last marginally longer than a standard AR before needing replacement parts to keep running reliably.
The only problem is diminishing returns. This is true in general, of course, but it's especially true with brute force solutions like this. If I remember correctly, Aermet 100 has roughly twice as much tensile strength as Carpenter 158, but costs about 3x for raw material alone, even before you account for how much harder it is to machine - and that's the best price-to-benefit ratio on my list.
(This is probably why Aermet bolts are gradually making their way in via LMT and KAC, but not anything else.)
I suppose that’s fair to say, but my mental taxonomy still considers the Knights Armament SR15 and LMT Monolithic Rail Platform to be AR’s. It seems like one could make a pretty strong argument for the SR15 at least, since I believe it was partly designed by Eugene Stoner. Then again, it is also the least compatible out there given the completely proprietary bolt design.
But that SR15’s proprietary bolt design by all accounts solves the bolt longevity issues, and the LMT MRP solves the rail and interfacing fragility issues. But you’re right that I don’t think there’s any single AR that solves both simultaneously. LMT’s BCG is improved but I don’t know that it solves the problem as well as the SR15.
I’m not sure it’s fair to hold the stock mortaring situation against the AR, since this same issue appears in virtually every collapsible polymer stock design. It only is not a problem with fixed stock designs, independent of whether they’re an AR or not. I believe the FN Scar for example received a lot of criticism for its stock being considerably more fragile than even standard M4 stocks.
Also, I’ve never heard of dust in the magwell being an issue as long as standard practices like keeping a mag in place in dusty/dirty environments are used. In fact, more often I’ve heard of issues with polymer AK mags breaking, since the AK mag design essentially offloads the rigidity and durability problems to the mag rather than the rifle. This could be a good or bad thing in some ways, but I think everyone agrees it increases weight too much when you need steel mags. Example: All modern designs use enclosed magwells and polymer mags.
In any case, I’d be inclined to concede to you that ARs don’t last as long as other designs (without replacement parts every 5-10k rounds or so). And it certainly makes sense too when just dry running the action: compare the locking/unlocking cam action on an AR, vs a modern piston design like a Steyr AUG, FN Scar, CZ Bren, etc. and it’s so obvious how much less violent the forces are on the bolt as it locks/unlocks considerably slower and smoother on these more modern designs.
P.S. Fun fact for interested readers: All these “more modern” designs I mentioned are all descendants of Eugene Stoner’s AR18 design (which is itself a descendent if others though, of course). The influence of Stoner’s design in modern rifles is impressively prolific. If you want to learn more fascinating trivia, I recommend the YouTube channel “Forgotten Weapons” which is incredibly educational.
In practice, I think we mostly go by "I know it when I see it", which usually works because most cases are clear-cut. But then you get designs like, say, ARAK-21 or SIG MCX, where it could be reasonably argued either way - and no matter how you argue it, it just muddies the water further.
Let's take MCX, for example - is it an AR? If it is not, then what exactly pushed it over the line? Piston? But we have piston ARs. Incompatible lower and/or upper? Then CMMG Mutant isn't an AR, either. Recoil spring in the receiver, and no buffer or buffer tube? Extar EXP has the same arrangement, but is otherwise a conventional Stoner action.
Okay, so suppose it's an AR. But nobody calls SCAR an AR; so what's the difference between SCAR and MCX that makes the latter an AR?
I don't really have an answer here, if the difference is meant to be qualitative. On the other hand, if it's not about one particular difference, then we could draw a line somewhere and say that it needs to have that much in common - so one difference doesn't push it over the line, but in aggregate, enough of them can.