MachIVshooter
Member
Not a pro, since it makes the design less flexible in the end
Not a pro, since it makes the design less flexible in the end
Kind of forgetting that the design started out as the 7.62x51mm AR-10 aren't you? It worked rather well in that configuration too.Yes, Mach. The AR15 cannot be adapted much beyond 223 at all without significant redesign, nor much below it, either; you're pretty much stuck with an intermediate cartridge absent major changes to the gas system (long-stroke SIG MPX or DI with large port 1/2" from the chamber) or a wholesale scaling to a different design regime (AR10). Adapting to a 14" barrel vs. an 18" barrel (along with swapping lots of gas & buffer components) is not the height of flexibility. Frankly, the fact that the AR readily allows 2/3rds of the gun to be removed & replaced as a unit (the upper) does not make that 2/3rds chunk particularly flexible, itself.
The AR15 cannot be adapted much beyond 223 at all without significant redesign, nor much below it, either; you're pretty much stuck with an intermediate cartridge absent major changes to the gas system
Adapting to a 14" barrel vs. an 18" barrel (along with swapping lots of gas & buffer components) is not the height of flexibility. Frankly, the fact that the AR readily allows 2/3rds of the gun to be removed & replaced as a unit (the upper) does not make that 2/3rds chunk particularly flexible, itself.
The true pinnacle of modularity, such that there can be one, is probably the HK roller guns, though I hate to admit it; short to long barrels, pistol cal to belt fed LMGs, suppressed SBRs, and even a sniper rifle --and they can pretty much all take eachothers' stocks, trigger groups, and in some cases BCG components,
90% of what you just posted was either designed specifically for the AR, or is so small it doesnt even use the AR gas system or rotating bolt but operates as a straight blowback.. barnbwt was right, its a pretty inflexible design and the fact most of the cartridges for it are cartridges designed specifically for it speaks volumes of itThe platform is chambered in a plethora of cartridges from .22 LR to powerful mid bore magnums to big bore thumpers that rival the .45-70. If you want to limit it only to the smaller AR-15 platform (and exclude rounds that won't fit the magwell), you still have:
.17 HMR
.17 Winchester Super Magnum
.22 Long Rifle
.22 Winchester Magnum Rimfire
.17 Remington
.17×223
.204 Ruger
.223 Remington/5.56 NATO
.243 Winchester Super Short Magnum
.25 Winchester Super Short Magnum
.25-45 Sharps
.270AR
.277 Wolverine (6.8×39mm)
.30 Carbine
.30 Herrett (.308-6.8)
.30 Remington AR
.300 AAC Blackout (7.62×35mm)
.300 Whisper
.375 Reaper
.40 S&W
.45 ACP
.450 Bushmaster
.458 SOCOM
.50 Beowulf
.50 Action Express
5.45×39mm
5.56×42mm(5.56-6.8)
5.56x45mm NATO
6mm-223 Remington
6mm Fat Rat (6mm Grendel AI)
6mm AR Turbo
6mm BRX
5.7×28mm FN
6.5mm BRX
6.5mm Grendel
6.5mm Patriot Combat Cartridge
6.8mm Remington SPC
7.62×37mm Musang
7.62×39mm
7.62×40mm Wilson Tactical
9mm Parabellum
10mm Auto
Seems pretty flexible to me.......
WTH are you talking about??? We run my SOT friend's FA M-16 lower with uppers from 7.5-20", suppressed and unsuppressed, 5.56 & .300 BLK, all using a carbine buffer & spring. It even rocked and rolled flawlessly with my ultralight upper, in which I milled away nearly 3 ounces of the carrier. No bolt bounce, no hiccups of any kind.
The ridiculous debates people get into about the "right buffer" are just that. Except for my rifles with rifle receiver extensions, all of mine are running standard carbine buffers with barrels from 7.5"-18", and they all work just fine. And plopping my 22" bull barrel upper on a carbine lower creates no issues whatsoever, aside from poor balance.
Sure sounds a lot like the AR, don't it?
90% of what you just posted was either designed specifically for the AR, or is so small it doesnt even use the AR gas system or rotating bolt but operates as a straight blowback
and five of those are based on 5.56 or a nearly identical cartridge (17 remington, 17x223, 204 ruger, 300 whisper, and 6mm-223), two of them suffer reliability issues (the soviet rounds), the two WSSMs require an entirely redesigned upper, and the .50AE might as well41 cartridges listed. 10 of them were not designed for the AR and do make use of the gas system.
.17 Remington
.17×223
.204 Ruger
.243 Winchester Super Short Magnum
.25 Winchester Super Short Magnum
.300 Whisper
.50 Action Express
5.45×39mm
6mm-223 Remington
7.62×39mm
10/41 is one quarter, not one tenth. You need to temper the hyperbole, my friend.
This list I snagged quickly, of course, does not even include numerous other rounds that would obviously be suitable, such as 7.62x25, 9x21, 9x23, 9x25 Dillon, 9mm Win Mag, .45 Win Mag, .400 Corbon, 10mm Mag, .44 AMP, .440 Corbon, or any other round which will physically fit through the mag well. Some would require proprietary bolts, may or may not use the gas system, but will function in the AR-15 regardless.
Could most of these be adapted to other platforms that fire intermediate rounds? Sure. As easily as the AR? Generally no. Some of you contend that "swapping the complete upper doesn't count because it's most of the gun". I submit to you that, while upper swaps make caliber changes a 5 second affair, that doesn't mean most of the upper parts aren't also flexible. Save for odd ducks like the AR-57 or .50 BMG uppers, they are all using the same upper receiver, barrel nuts, hand guards, charging handles, gas tubes, and generally the same gas blocks/FSBs. So, caliber change requires a different barrel (true of any gun), sometimes a different bolt (also true of any gun, but a cheaper and smaller component in the AR than most), and a different carrier for blow back applications. Wow! A whole 1-3 upper parts are different for a range of more than 40 cartridges.
Find me another semi auto rifle that can boast that. Can you take your AK into the garage with just a new barrel and a single tool, and walk out 10 minutes later chambered for a different cartridge? How about your HK? FAL? Galil? The SCAR would be the only one easier, and it has limitations of it's own.
and five of those are based on 5.56 or a nearly identical cartridge (17 remington, 17x223, 204 ruger, 300 whisper, and 6mm-223), two of them suffer reliability issues (the soviet rounds), the two WSSMs require an entirely redesigned upper, and the .50AE might as well
Nothing gained except an understanding of why DI doesn't seem to appear in any other configuration...
From what I've seen, the temperature differences are small enough to be irrelevant, and certainly not in the range that would burn off lubricant. And if you shoot a full-auto M16/M4 magazine after magazine after magazine until overheat failure, the bolt and carrier are still fine. In an M4, the first component to fail will be the barrel.Wait, I thought this was common knowledge & the subject of countless piston-conversion infrared comparison tests showing reduced temps on operating parts. The impact of this difference is debatable (effects on material properties or burning off of lubricant) but the bolt/carrier are simply hotter --during sustained fire-- than piston designs that keep the hot gas further away.
And yet the AK is typically cited as the ne plus ultra of semiauto reliability. I guess the minimal powder fouling that blows into the receiver from the gas system isn't a reliability issue with the AK any more than it is with an AR.This is because, like the AR, the AK's gas tube is largely vented into the receiver. Guns with tighter piston tubes (AR70 is my personal exposure) do not have the issue, nor do any of the short-stroke designs which are basically the cleanest non-recoil-operated systems there are. Please go on and explain how an AR10 vents just as much fouling into the receiver/FCG area as my FNAR which remains clean for hundreds of rounds, though. I would also recommend looking over a slo-mo of a MAS49/56, which shows that a large volume of gas is delivered through the gas tube (which is very similar to the AR, the bolt-end of things not so much), without a corresponding 'puff' as the bolt retracts.
Then we agree.For like the third time, I'm not saying these are issues in practice.
I'm not. I'm taking this as a discussion on the technical merits of DI vs. forward-piston systems. I'm still an AK fan at heart, and shot USPSA carbine for a while with a SAR-1, but I moved away from that platform due to the greater accuracy and flexibility of commercial .223 in the AR platform. The Stoner-style DI system has shortcomings, but they are not in the realm of reliability or durability; they are in the realm of working with really short barrels, or suppressed rifles, without a lot of tinkering.Please stop taking this as me 'knocking' your baby.
I'm citing DoD tests (specifically the M4 vs. M4A1 trials), not some dude on Youtube.Gas tube ruptures are not unheard of modes on those moronic 'torture tests' garnering all the Youboob hits. Super hot gas, thin wall stainless tube, blammo. I believe the couple I saw were on heavier barrel wannabe-SAW platforms, FWIW (I agree the barrel is long toast on pretty much every automatic there is given sustained full auto).
I think that is an assumption. The gas system of a forward-piston design is subjected to far higher temps than the gas system of an AR, and I have yet to see any forward-piston system subjected to a similar heat load test as the Army M4/M4A1 tests. Remember, the piston on a SCAR or an AR piston variant sees the same heat load as the very front of a DI AR's gas tube and gas block.My point in raising this aspect is that the gas system of the AR is ultimately 'weaker' --i.e. more prone to bursting or failing due to overheating-- than piston designs, and this is largely due to the fact that pistons necessarily have beefier parts.
No, because it is only the diameter of a pencil, so you could significantly increase the wall thickness without increasing the weight much. But there's no need, because on a civilian rifle there is simply no physical way to get the gas tube hot enough to fail from overheat.If you made the AR tube as beefy as an AK/etc's, it would likely be just as durable, but also just as heavy.
There's more variables at play between AR/AK than just the similar action-fouling concern. There's obviously both looser parts and (too much) more empty space in the AK from 'stuff' to fall out of the way. Agree that any fouling/failure mode is generally a non-issue for all gas operating autoloaders invented since the M1, but compared directly to each other the AK can tolerate more 'stuff' being blown into the action area*. The trigger group especially seems more tolerant, if only because there's a much larger way out for debris near the sear.And yet the AK is typically cited as the ne plus ultra of semiauto reliability. I guess the minimal powder fouling that blows into the receiver from the gas system isn't a reliability issue with the AK any more than it is with an AR.
There's more variables at play between AR/AK than just the similar action-fouling concern. There's obviously both looser parts and (too much) more empty space in the AK from 'stuff' to fall out of the way.
As far as the other points of mine you addressed, you are mostly right; they really don't matter for our (or really anyone's) applications. But, seeing as the topic of the thread was "Why isn't DI used anywhere else if it's so popular/dominant/successful in the AR" so I was highlighting what seem to be the only logical/technical explanations that don't involve some secret AR Fanboy Cabal manipulating the arms industry from behind the scenes (oh wait, that's exactly what the DOD is at this point to a large degreee! )
There's more variables at play between AR/AK than just the similar action-fouling concern. There's obviously both looser parts and (too much) more empty space in the AK from 'stuff' to fall out of the way. Agree that any fouling/failure mode is generally a non-issue for all gas operating autoloaders invented since the M1, but compared directly to each other the AK can tolerate more 'stuff' being blown into the action area*. The trigger group especially seems more tolerant, if only because there's a much larger way out for debris near the sear.
And unlike these true DI designs, the AR has a piston in the carrier and is not DI! Arghh!No idea but the Swedish Ljungman (and derivative Egyptian Hakim) are DI and predate the AR.
Unless they changed something recently, all the Nemo .300 Win Mag AR-type rifles are DI and not piston (yes, I know the AR isn't a true DI, but that's the simplest way to differentiate it).Hookeye said:If I had the coin I'd like to give a Nemo .300 Winmag a try.
Not sure what gas system it runs, but it is laid out in AR style platform.
if it had the flexibility to reliably shoot 7.62x39 there likely wouldnt be a 300 blackout or a 7.62x40WT, but since the magazine well prevents tapered rounds from reliably feeding and the bolt is prone to breaking with larger bodies cartridges, these two cartridges as well as more 30 cal wildcats have to be made specifically for the AR instead... even 5.45x39 has its issues