https://www.marinecorpstimes.com/news/your-marine-corps/2017/12/11/new-in-2018-corps-adopts-m855a1-round/

The Army’s M855A1 round has proved a deadlier bullet than the Corps’ M855 5.56mm round, said Chris Woodburn of the Corps’ Combat Development Command.

“The M855A1 provides improved performance over the current M855, 5.56mm round in a lead-free form factor, and provides improved steel penetration, hard- and soft-target terminal effects, with more consistent terminal effects than the M855 at ranges out to 600 meters,” Woodburn told Marine Corps Times.

In testing, the Army round caused “some durability issues” for the ­Marine Corps’ M27 Infantry Automatic Rifle, Brig. Gen. Joseph Shrader, ­MARCORYSCOM’s commanding officer, told Senators in June. Even though the M855A1 reduces the IAR’s durability, the M27 is still “operationally suitable” when firing the Army rounds, Woodburn said.

So the HK rifles aren't as awesome as they/joglee make them sound?

Unpossible

You're in a joglee thread, friend.

And he changed his opinion after hearing from some true SMEs on the M27/HK416.

Thread content: Somewhere in Germany, an HK executive greedily rubs his hands together while marking up the price of Das Bolts.

Apparently some months back Joglee got red pilled by someone knowledgeable about the HK416/M27, especially in terms of what happens when its ran with M855A1.

Shouldn't they have been comparing it to the Mk318 Mod 0/1?

HK rifles are garbage for the money.

I've posted the testing results that showed the M27 was less reliable across the magazine spectrum than the M4A1, it only performed as good with 1-2 magazines and it broke bolts at nearly the same rate as the M4A1 did.

I believe the M27 attained around 3 extra magazines before its bolt broke.

Took us long enough. I would be interested in seeing if material changes could extend bolt life.

The M27 already uses steel that exceeds Carpenters C158, from Aubert and Duval of France.

Although the whole roller burnishing thing RDECOM showed off looked promising with it's guaranteed doubling of bolt life to exceed 20,000 rounds.

This is a bigger takeaway IMO in that article

Neller is considering replacing M4 carbines in infantry squads with IARs. In February, MARCORSYSCOM expressed interest in buying 11,000 weapons meeting the IAR's requirements.

In the back of my mind I had always thought this was the endgame with the IAR.

Doubtful it happens. The M27 costs 5x what the M4 does and breaks bolts at the same rate. One would have to be stupid to spend that much when replacement schedules will remain the same.

Talk about spending yourself into a hole, need a bolt at 9,000 rounds? Gonna cost you the same as 5 M4 bolts, same for every part on the weapon except maybe the barrel.

I wonder how S7 would compare.

I approve. It’s a great round.

Not endgame, but end result. The IAR was a concept design before anybody knew what an HK416 was, designed to be more practical for rifle team applications than a belt fed LMG that were at the very tail end of their service life, which also had significant tactical drawbacks demonstrated in the GWOT. But in choosing the HK416 over other varieties of IAR competitors that were open bolt or mixed closed/open bolt the USMC got a good automatic rifle but also found out that with the ACOG, standard bipod, great trigger, great barrel, that it was also a pretty damn good DM rifle too. And all told its not "significantly" more money than a Colt M4 with the shitty non-freefloat RAS rail, shitty 3 rd burst trigger, and shitty 3-4 MOA accuracy. The end result is the conclusion of why have a single IAR per fireteam if everyone in the platoon can carry an IAR to play doorkicker rifleman, play DM, play auto rifleman?

The issue is that current configoration of HK416 and M855A1 don't play well together, and HK apparently is fucking around with cost. So fuck HK, go LWRC M6a4 or something else that runs well with all ammo, is piston driven for auto and suppressed use, is accurate, reliable, and wont break the bank issuing them out only to 03xx in victor units. Give this to EVERY infantry Marine, issue M249 if mission calls for it only, same with M3A1 MAAW.

A "support" weapon fed from box mags is pants-on-head retarded to begin with.

Its cool looking

Current M4, what are they paying, sans optics?
M27, sans optics and deployment kit, what are they paying?

Exactly.  Fuck that gun, find one that works with M855A1 because it's tits.

Would it shock you to learn that the German MG34 in the squad LMG role was designed to be with either a 70 rd top cover magazine (the entire feed tray assemble would need to be removed and replaced to use belts), or using a snail drum with belted ammo and ten less rounds than a Magpul 60 round drum holds but weighed twice as much?

Appears that way to me as well, but I don't kick in doors or do anything remotely like that for a living. It would seem that you would lose a large portion of your suppressive fire ability to a squad in order to add another rifleman.

M4A1(SOCOM barrel, RAS, full auto trigger, ambi safety, etc) runs around $650 or so, M27 runs closer to $2,500-$3,000 sans optic.

Then you have the issue of the M27 barrel having to go from France, to Germany, to the US as well as the cost of said barrel.
We can't cheaply make the M27 barrel here because the blanks are sourced from one company on the other side of the globe.

What the 416 offers over the M4A1 is a better barrel, and rail system that's it. It breaks every other part at nearly the same intervals thanks to numerous mods that the M4A1 doesn't have(like disconnector plates, firing pin safeties, etc) but costs 5x as much to maintain. I also believe the M4A1 is averaging closer to 1.5-2moa with M855A1.

But didn't they ditch all that crap and use the MG-42 which was FA only and had a higher rate of fire? I always enjoy your posts.

I guess I'm old fashioned but I don't understand why they went away from the A4 with the ACOG.  That was a fuckin winner...BOOM! Headshot!!

They shouldn't load it so hot. I can hit 3k fps without breaking things in a 16" barrel.

Glad you brought up door kicking, because it was a primary reason belt fed weapons don't belong in the squad. An open bolt weapon, belt or magazine fed, has no certainty it will fire a single round when the trigger is pulled, thus it is a liability in urban warfare that requires everyone in a rifle squad to be able to get into a stack and clear a room. So what good is a squad support weapon when it limits that person to not being able to effectively perform the duties of a squad member?

Times have changed. Most of what we know about machine guns stems from the traditions of when they were created in the first place. Belt fed came about because in the late 19th century and early 20th century magazines sucked. Their springs sucked, their followers cucked, their design angles sucked, their lips bent, etc. not Maxim nor anyone else were designing individual magazines that were interchangeable and reliable, especially under full auto, less alone high capacity, which meant 20 rounds back then, so they instead went a different route. By adding a well made steel springs in the top cover pawls of the feed tray, the machine gun could reliable feed itself by pulling in some sort of cloth, metal, or disintegrating belt of ammo. Can we do magazines better now? Fuck yes. Even Magpul has reliable 60 round drum mags, AKs have reliable 75 round drum mags. Open bolt is great for full auto, sucks for accuracy (mass of entire bolt moving forward under spring tension upon trigger pull has a tendency to cause movement of sight picture), and is detrimental to close combat.

Open bolt came about because early machine guns were designed to be fired continuously, indefinitely, an open bolt is the only way to prevent cook offs, out of battery detonations, and other heat related malfunctions. Yes, open bolt helps but is it necessary? Experience with the M27 has proven its not needed, that IAR can fire its entire standard issue with no heat related malfunctions. The HK416 is only open bolt, going to a LWRC or Colt means closed bolt while the weapon is in semi, and open bolt on auto, thereby giving the accuracy necessary for slow fire, with the cooling factor in auto fire.

Also, let's talk reloading. How long does it take to reload a 60 rd Magul drum with another? Now compare that to reloading a 200 round box or a 100 round nutsack on a M249. The latter takes 3-4x time longer. It takes longer to perform immediate action, it takes much longer before its safe to perform remedial action.

Let's talk training. A LMG is a machine. It has a shit load of parts and a very complicated cycle of operations that needs to be fully understood by the gunner for them to know how to clear it when it does jam, or to understand what might be wrong with it by noticing how its acting. In the Marine Corps and Army they are issuing LMGs to low ranking dudes who are not always adequately trained to use them, and what normally happens is that by the time they become very knowledgeable they end up getting promoted and being made team leaders, who are not machine gun AGs or TLs whose job it is to stand right next to a firing LMG and supervise its use. Often a rifle team leader isn't even going to be within 10 meters of the SAW gunner in combat, they can't babysit them to deal with whatever fuck ups that can occur the same way a MG team leader can unfuck his gun teams when the gun goes down. Meanwhile, every Soldier or Marine already knows how to use an AR15 style IAR, they already are trained on it, they know how to properly strip and maintain it (hopefully), they have the pouches for it, the mags that work with it (so the Squad support weapon can be fed by EVERYONE in the unit).

Now couple the fact that the IAR doesn't just do automatic rifle duties. It also does designated marksman duties. While also being able to do basic rifleman duties (door kicking, trench clearing, etc).

Closed bolt you mean?

Honestly the M249 is a crappy LMG to begin with. I'd rather see something like the KAC X-LMG compared to the IAR concept. I mean it's 5.56 and weighs nearly as much as a M240, while using the horrible upside down AK operating system.

A LMG that weighs 10-11lbs and is actually designed well.

Did Mk 318 fall out of favor?  I understood it to be an excellent round.

Congress didn't want to buy both Mk318 for the USMC and M855a1 for the Army.

Yes, they ditched it. The MG34 was not reliable in dirty or cold conditions and new methods were being developed to make production more effective for stamp machining. The high rate of fire worked well because MG42 were often shooting at things that weren't people, it being the infantry battalion's only air defense weapon, it needed a very high rate of fire to ensure hits on fast moving low flying enemy aircraft. The high rate of fire was thought to work well for bipod firing, as the weapon would get off more rounds before the shooter was beat to fuck out of position from the heavy 7.92mm recoil, they basically considered it a shotgun. That was the theory, but the reality was that the cone of fire was still an initial shot dead on and subsequent shots going higher and higher, so as a shotgun its pattern was a straight line upwards, so the likelihood of hitting a point target multiple times was not significantly increased unless the weapon was fired from a pintle mount that absorbed some recoil, off the tripod at a point target, or superbly loaded on the bipod by a very competent gunner shooting from a near perfect position. In the tripod mounted HMG role (Germans didn't have water cooled, being GPMG they used their MG34 and MG42 for that duty too by switching barrels as often as needed, with gun teams carrying 3-4 spare barrels headspaced to that one weapon) the high rate of fire was actually detrimental, as it limited the length of time the gun could be fired due to ammo concerns (it fired twice as fast as other HMGs, necessitating twice the ammo), or if fired in very short burst (1 second=ten rounds), it couldn't fire as many bursts as needed to adequately suppress an area target for extended periods. The purpose of a slow rate of fire for a MMG is largely because slow is better than fast with area fire.

The greatest achievement of the high rate of fire was with reliability, the MG42 being delayed blowback operated meant that if the gun was dirty as hell, the ammo filthy, everything frost covered, its rate of fire would slow but the timing would still not get fucked up. So in perfect conditions they fired 1,200-1,500 rpm, but in cold, dirty conditions they'd fire 800-1,000 rpm, they still fired. In the same conditions, the MG34 simply would not fire.

Another factor that worked well with the high rate of fire was the psychological factor that came from the sound of the gun firing, which sometimes would ground advancing infantry. Similar to the fear induced by the sound of tank engines approaching, the terror sound of incoming Nebelwerfer rockets, the MG42 did have a magnified suppressive role because of the sound of its rapid shots.

Lastly, and this can't be emphasized enough, by the time the MG42 was being issued out in mass the Germans were largely relegated to defensive warfare. Any machine gun, even a Chauchet, would have been effective in those situations. Weight was often not a concern, movement of ammo was generally not a concern, they were often firing from prepared positions at enemy they could channel into kill zones with obstancles, knowing the ground in advance allowing them to target avenues of approach, etc. While the Germans had very serious problem having enough artillery and mortar rounds, and radios to guide them, they always seemed to be able to make enough small arms ammo and supply it to the front lines, so that also increased the effectiveness of their usage.

MOUT.

The barrel doesn't need to be 20" to kill, or even hit targets if you know the ballistics (thanks to the ACOG). And the stock being able to collapse greatly helps in tight cramped spaces, for adjusting length of pull depending on armor or clothing worn.

Overall, shooting is easier and individual movement easier with a smaller weapon than a larger.

The barrel is the weak link of the AR-15 (not the operating system) in the vast majority of "fire until destruction" type scenarios.

A new operating system is not needed... at all. It solves a problem that doesn't exist.

If you want to use the AR-15 platform as an LMG, all it needs is a heavier barrel and a slightly upgraded gas tube (inconel).

If you over-gas an AR-15 and use a heavy bolt... it is extraordinarily reliable even in adverse conditions.

This is why most of the "piston" AR-15 variants are heavily over-gassed to attempt to sway reliability tests. Thats part of their retarded marketing schtick. Of course, this also breaks parts so it doesn't actually provide a net benefit under real testing. Same real world reliability with more broken parts.

Yeah, I wrote the wrong thing. HK416 was closed bolt only even though I believe the IAR trials specified a closed/open.

There are still many scenarios where a belt fed issued to the squad level would come in handy. Jungle, precision fire just aint happening. Some MOUT situations. Defending patrol bases from massed attacks from Hadji staging in villages only meters away from the front gate after it gets obliterated by a VBIED, etc. However, for that role I'd take a KAC LMG, Ultimax, or something similar in a heartbeat over the M249. And I'd still probably not make it a permanent feature in a squad's MTOE, just place it in company arms rooms for "Issue as needed" conditions. Same for Carl Gustav, or even how we do Javelins when issued to non anti-armor sections.

PL to SL: Your squad is pulling blocking position duty on the upcoming air assault. Expect heavy enemy contact.
SL to TL: Have one of your dudes go draw the KAC LMG and the battle belt rig with ammo, I want your team working the SAW.

Meanwhile everyone else pulls DM duties, because they have the weapon, optic, ammo, and training package to pull it off.

MG42 had drums as well, iirc, though they were simply rigid packs holding 60 or so cartridges in a belt (similar to modern ammo boxes for portable belt-feds)

I guess momentum is the strongest factor in life.

It was about logistics. By going M855A1 the USMC could use Army stores while deployed and not have to rely on their own specialty ammo.

I'm not fanboi of HK or piston guns, and I'm not an engineer. But I've read that when it comes to short barrel (I guess 14.5" qualifies), lots of full auto, and suppressor use, piston is the way to go.

We're going to be using these carbines for rifleman and DM work, but also IAR duty, they need to be able to function well on full auto, and the times appear that all suppressor, all the time is likely on the horizon, so we better start designing our weapons to work well in full auto while suppressed. Because if we don't, we're still stuck with a weapon that either wont work well suppressed (which then means reliability issues or tactical problems from going sans suppressor), and eventually we're just going to have to fix that problem anyway.

Maybe a simple adjustable gas block on a normal DI gas system is enough. I don't know enough to answer it it, but however, adjustable gas regulator is something that NEEDS to be on the next service rifle.

I question how well it will serve the DM role after it has been used in the AR role.  Full auto fire has a tendency to degrade barrels.

Both adjustable gas blocks and more recently adjustable-gas bolts seem to be a better (and much lighter) option than a piston for accomplishing the same goal, but I'm not aware of any military testing on those. It seems like the logical answer but it's not as sexy as a new rifle and won't get some general a job at HK or whoever is building the next piston gun.

Why the blue hell would all copper bullets make an M27 wear out faster?  Are they loading these overpressure?

You best believe in Joglee threads.  You're in one . jpg

I also have issue with considering it inherently more accurate than the basic DI gun in the first place. If you put a better barrel and bolt on a FF M16 you'd likely get better accuracy than any piston gun, and for a fraction of the price of the HK you could buy some damn fine barrels and bolts.

AFAIK DI tends to be inherently more accurate than piston due to the lack of off-bore reciprocating mass.

yes, unless something changed with their specs since they were introduced

I'm just going from some InRange TV videos I've watched, but apparently barrel making has progressed quite a bit further than most of the barrel manufacturing techniques we're used to. Chrome lining can be done quite well to make accurate barrels (FN does it), better steel materials can be used, better forging and heat treating options, Meloniting extends barrel life, etc. We just have to accept that "Milspec" does not mean quality, it just means Milspec, often in reference to some decision made when JFK and LBJ were still President.

That and a simple active fix is if anybody besides an armorer for testing purposes decides to dump an entire mag or drums on full auto, in training or combat, they get BN level Art 15/NJP and reduced by one rank. No questions, no excuse, its automatic.

Depending on the magazines the steel tip are hitting the barrel extension at a weird angle and gouging it. And overpressure is hurting bolts.

But do they both work as well as piston for full auto suppressed? There is going to be more blowback of gas into the upper receiver and BCG area, and its going to be happening more so much much hotter gas and more of it. A piston gun you're controlling the rate of fire better and only gas back into upper is blowback from can. With DI, all the normal gas from firing plus blowback, so double it.

Again, I don't know more than what I've read on this, maybe this is just a simple engineering project. But my understanding was CAG specifically went with the HK416 because they were expecting to go short barreled (10.5-14.5), go full auto, and go suppressed.

My understanding from previous threads about M855A1 in M27 is that the M27 was designed before M855A1 existed, and thus is not designed for the higher-pressure M855A1.  While today's M855A1 is not as high-pressured as the original M855A1, it is still a significantly higher pressure than M855 or Mk318.  This higher pressure is not what the M27's system was designed for and thus it has a reduced lifespan when using M855A1, now about on par with an M4A1.  Which sucks when the point of paying 3-5X the price of an M4A1 for an M27 was to get extended life beyond an M4A1's.

SMEs, if I am wrong, correct me.

This too.

Thank god HK makes a non spec magazine well.

because, proprietary bullshit.