I've ran my 10.5 416 upper with a gemtec G5 for a while and never had any issues.   Guess I'm lucky....

but what ammo and how much?

Mine ran well for a while too, until it didn't.

62gr  green tip,

I'm sure you've heard the old saying "There's more then one way to skin a cat."

HK's first attempt at the 416 gas system was a direct derivative of the G36 piston system in that it's a semi-self adjusting system that accounts for slightly under pressure and over pressure ammunition by opening the gas vent on the gas block with the nipple of the piston either slower or quicker depending on the pressure buildup (or lack thereof) of the ammunition.

With the first generation of guns, the barrel gas ports were all identical and the only change for barrel length and dwell time was the size of the vent on the gas block to allow more or less gas and pressure to vent quicker or slower.

Unfortunately without thought towards suppressors, the initial short barrel gas blocks had no vent at all to make up for the diminished dwell time, which is even less then that of a MK18 due to the gas port being further forward then a DI gun.  This also removes a fair amount of the built in "self adjustment" feature as there is much less time for the system to trap pressure in under powered ammunition and the system was pretty much "factory tuned" for milspec ammunition, running unsuppressed, but even then it was slightly overgassed with milspec ammo.

What it boils down to is that the shorter the barrel in relation to the length of the gas system, your window of opportunity and adjustment to the system decreases dramatically. Tuning the system becomes much more difficult and is a phenomenon that we've already experienced in the DI world with so many manufacturers over porting the 10.5 guns to be able to run with weaker civ ammo and being stupidly overgassed with milspec ammo.  Even some high end manufacturers went down this route so they wouldn't have to deal with people bitching about wolf ammo not cycling their guns (Noveske even ported out to .08 on the 10.5 N4 line))

HK really pushed to be so different that they strayed from tried and true methods of controlling gas in the gun that it created a new host of issues that were easy to overcome had HK simply not forced themselves into the box of using the vented gas block rather then adjusting the barrel itself.  

Enter the adjustable gas blocks, which as some have pointed out, introduce more small, moving parts into an otherwise near bulletproof and idiot proof system.

And then HK finally realized that controlling both port and vent together made for a much better solution in the short barrel guns and started enlarging gas ports in shorter barrels (something that I recently learned myself only after having my own experience in the matter with my personal gun.

The experience I had was with my personal HK upper that I purchased as a 16 inch barrel and then shortened it to 10.5 and dropped it on an SBR.  Since I am more knowledgeable in DI matters, and I knew of the issues that HK had with early 10.5 guns, broken discos, etc., coupled with the fact that I didn't want to go buy a different gas block, I kept the standard gas block and started enlarging the gas port one size at a time until I came to a perfect size that allows full function and lockback on the last round every single time unsuppressed, and is much easier and less abusive on the gun when running suppressed.

For those who like to observe ejection, unsuppressed throws brass to the 4 to 4:30, and suppressed throws towards 2 to 2:30 o'clock position.  Recoil is minimal for the system, dot bounce is much less then even a factory 14.5 gun, and it's highly controllable.

Currently the suppressor is an AAC 762 sdn 6 with a brakeout 2.0.   This has also had the very nice side effect of having virtually no zero shift when shooting unsuppressed or suppressed. I have also run it with a Gemtech M4-96D using a birdcage bi-lock, so I know it isn't just the brakeout 2.0 doing all the work for me, although the brakeout does help even more. A brakeout 1 made it shoot like a .22LR in terms of controllability, but I can't stand the blast off the brake.

What all this means is that given HK's desire to stick with their solution regarding gas block mods and my (and most people here) experience with DI dynamics, My personal opinion is that using the best aspects of the original HK system modified with many years of DI engineering regarding barrel lengths and gas ports, produce optimal performance without adding extra crap into the mix.

Was the 416 "unusable" in it's early configurations as some have said? Absolutely not. But it also wasn't the perfect "jack of all trades" that it was envisioned as.  It's upgrades were just that. Upgrades, not complete system redesigns.  Just like the M16 and all of the modifications since the original design left Eugene Stoners hands. The concept was sound and it just needed some tweaking once it left the sterile factory and hit the real world.

Lastly,  on a different note, In this thread, like so many others, I see many statements about issues with little or no supporting evidence. A lot of hand wringing and purse swinging without any fact, just opinion.  It's one of the things that's always irked me about the tech forums.  Facts and data are demanded about DI systems but rumor, supposition, and assumption are ok to fling at piston system, mostly HK.

I've seen, used, repaired, and had a fair amount of experience with the HK guns.  I've even broken a 416 bolt in my personal gun.  I've busted and replaced more DI bolts in my life though. Shit happens.  We had a freshly deployed unit bring a bunch of guns in for inspection in afghan and in a single day I shitcanned the bolts in 75% of the guns I inspected that day for cracked bolt lugs on either side of the extractor.  Does that make the M4 a shit gun? Nope, it simply means those guns had been well used and did their fucking job.

The 416 has held up well with fewer bumps on its road the the m16 has and is steadily gaining steam because it IS a good weapons system. The functionality of the 416 comes from the fact that it's gassed for strong springs and a heavy weight buffer. The concept was to have a system capable of pushing past heavy fouling and be more reliable in shit conditions that didn't contribute to it's own fouling. To that end, when "tuned" in the same manner as a DI gun with that extra weight and stronger action spring, rather then trying to simply overgass the system to the point of stupidity, the gun has a LOT of potential.  HK just needs to remember that conventional porting experience in DI guns exists for a reason and while the nippled piston system is a great system, it's a concept that will work better with a little conventional wisdom thrown in rather then trying to make everything different just for the sake of being different.

If the gas port is its optimal diameter to run unsuppressed only, is it the same diameter to run optimally suppressed only? No, so my previous assertion stands. What some of you refer to as crap and complexity, is the solution most major manufacturers (including Hk!)  use to optimally run suppressed and unsuppressed, the AGB. Your mod above is a compromise.

Edited for spelling error

i dunno man....cracked bolts in that many rifles? good thing none of those lubgs broke off and got stuck in the barrel extension, if a soldier died because of that, would you still say the rifle did its job correctly?

how often do you see cracked bolts in the same number of DI M4's?

also you called that batch M4's, those were hk416s right? isnt that technically a differnt creature?

i dont think i'd trust that HK rifle with 855a1 over the long haul with my life. i would probably trust them with other ammo though.

I would disagree.

If the port is sized so that the gun functions perfectly and locks back on the last round every single time unsuppressed, yet also doesn't exhibit severe overgassing indicators such as the bolt outrunning the magazine, etc. when suppressed, I'd call that being exactly what it needs to be, not a compromise.

Keep in mind that the 416 is much, much more efficient with its use of the gas diverted from the barrel then a DI system AND it has a somewhat self adjusting gas system from the get go (pressure dictates piston speed and piston speed dictates how quickly the vent opens as the nipple on the piston retracts).  This allows a wider operating range when modding the system to run suppressed.

It's an unfortunate thing that A DI gun must almost be at the low end of gassed (with ammo variances sometimes taking it fully to undergassed) to be properly "tuned" to run with a suppressor. And forget using a wide variety of milspec or SAAMI grade ammunition. That just makes it frustrating because you have to basically tune the gun to a single kind of ammunition whereas with the 416, my simple tuning trick works with every type of ammunition I've run through it from wolf to m855 to M193, to 75grain hornady TAP and a few others in between.

That's not what I would call a compromise. That's what I would call "working as it should".

You read incorrectly. The many cracked bolts were on DI M4's and M4A1's in Afghanistan. And yes, they still did their job, but needed to be replaced due to failing visual inspection criteria.

I've only seen a single broken 416 bolt and that was on my own personal rifle after 2k downrange with it.  It was purchased used (unknown prior round count) and did not show visual signs of cracking before installation.

Regarding M855A1, Due to the efficiency of the HK gas system, it does take a bit of a beating with the A1. A terribly easy fix for HK were they to do it.  Because of the efficiency though, there is a wider range of modification allowed with the 416 though.

The M4 took a hell of a beating as well with the original M855A1 so they dropped the specs of the M855A1 round to lower pressures which allowed the M4A1 to continue running "as is" (keep in mind that the M4A1 MWO includes replacing the buffer with a 4.6oz H2 buffer).

Why does the HK have so much trouble with high backpressure cans?

Hk doesn't agree with you. Neither does most other major manufacturers. Neither do I.

They don't now.

And your actual, hands on experience with this is?

Frankly, I don't really care if you agree or not.  I've done the work myself, I monitored the results with each port size increase until I got the function exactly where it needs to be and that's how the system runs.  Your disagreement and personal bias has exactly zero bearing on the reality of the situation.


Bullshit.  

Once again, the HK system is much more efficient and hence reacts more to increased duration pressure.  Meaning that the vents simply aren't big enough to bleed off enough pressure fast enough to reduce the strength of cycle.  Barrel length and dwell time have a huge impact on this due to the efficiency of the system.

HK's problem is that they've tried (for the most part until recently) to stick with a single gas port size and only change the vent size as a way of controlling the gas in the system.  To further this, they started making the adjustable gas blocks which introduces more parts, more things to fail, etc. instead of sticking with the KISS principle.

The only real drawback of increasing both vent and port size in the 10.4" barrels is the extra sound coming from the gas vent when suppressed, but since it requires supersonic ammunition to cycle the gun, this is really a moot point.

The DI system has had just as many issues getting it to run reliably suppressed, especially in shorter barrels, which is why we have a million and one different mods we can purchase on the commercial market for civs, and the military simply went with the compromise of getting the system to "work" while accepting a much shorter round count life of the guns(MK18's).

DI works fine suppressed and unsuppressed.

If you monitored your results with each port size increase suppressed and unsuppressed independently, you'd find the optimal size different for each. Do you disagree? That's why using a single port size, and not an AGR, is a compromise. Just like the Mk18 you referred to later. Any piston gun without an AGR is a compromise suppressed vs unsuppressed, there's no getting around it. That's why major arms manufacturers use them, despite your claimed downsides of additional parts, etc.

That begs the question: "What is optimal?"  How do you define "optimal" with your obviously extensive knowledge of the subject?

I define it as working within set parameters of both primary and secondary functions.  Do you have any idea what these might be?

If so, enlighten us.

Sure.

The secondary functions you refer to are the compromise, hence "secondary". You can argue it as much as you want, this has nothing to do with me. The fact that you're trying to convince us that you know more than most major arms manufacturers is laughable. That said, carry on!

I broke a bolt in a Colt 6933 after about 500 rounds unsuppressed and 1500ish rounds suppressed. It broke right after a 3 day EAG carbine class. I called SAW/Ken Elmore to get a replacement and spoke with him for a good while on suppressed Colt rifles. Ken was of the camp that running a suppressor on a stock (in my case 6933) is a huge compromise. It will work, and you really need to put in something like a h3 buffer to get the longest life out of it,  but it is far from ideal. He firmly believed a DI rifle needs to be set up to run around the suppressor to avoid the issue I had with short life on a bolt.

He now sells a carbine built around this idea on his site. I've had two Colt bolts fail at low round counts, one was a crack I found prior to failing and the other was while shooting and it put the gun out of the game.

I did a piece on m4carbine dot net called Scar vs AR where I used some specialized test equipment to look at the cycle of operations of an DI AR, a SCAR, and a LWRC piston rifle. In my data, the AGR on the scar works as advertised shooting suppressed vs unsuppressed. The LWRC did not. While on the surface the LWRC seems the same as the 416, it is not.

I've yet to see a video showing piston bounce like this with the 416



I would love to get ahold of a A5 upper and get some data on it like I did the others and see how HK's AGR shakes out.


That said HK FTW, cue the techno music and sonar pings!

THAT is some "impressive" piston bounce!

would be curious to know what buffer was in that and what it looked like without a can attached. if they rigged that with a carbine buffer, thats not a fair test.

I didn't list any of the primary or secondary functions. I asked you to.  I already know them.

In other words, you can't answer and know pretty much nothing at all.  

Hell, for that matter, why don't you enlighten us all on what the major manufacturers think about this subject while we're at it.

You keep saying that what I do and what they do does not match, yet you don't exactly say what you believe their ideals to be, much less have the capacity to answer my question.

Figures.

Continue on with yo bad self you youtube certified gun expert.

Buffer has nothing to do with piston bounce in a short stroke system.

The piston bounce shown happened while the bolt was still in cycle and not in contact with the op-rod.

The buffer only has effect on bolt carrier bounce.

No, I just prefer not to argue with gun bubbas on the internet.

You want to know what major manufacturers think?!? They choose to use AGRs for optimal suppressed and unsuppressed use. The Hk416, which is what this string is about, is on at least its 3rd version of AGR. Yeah, we get it. They're all wrong. And your the world's greatest undiscovered firearms designing genius.

For you to say, your setup isn't a compromise is like saying your suppressor adds no back pressure... magically.

Let it go man.

Gun bubba, that's funny.

Your problem is that you don't know enough to know what you don't know.  About the topic at hand or your audience.

I thought about actually explaining the real differences between the system, but that would clearly be a waste of time.  But I will offer the following advice:

Firstly, educate yourself on how the systems operate. No, really.  It's clear that you don't know the differences in how the DI and short stroke piston systems actually work and why one actually works better in some situations compared to the other or why it was possible for me to do what I did.  If you don't understand even the most basic principles of how the systems work, you'll never be able to comprehend modifications to the systems and how they truly effect function and why, so go learn. Start with the 8 cycles of function and work up from there.  If your only answer to something is "well, this is what the manufacturers did!" without any hands on experience or understanding why, then you've really no opinion on the subject much less one that matters.

Secondly, educate yourself on exactly how suppressors work and actually effect the operating systems (hint: they don't increase the pressure in the system).

And lastly, understand that sometimes you're actually talking to a professional who actually works on this stuff for a living, not just in a garage. Maybe even to the tune of 4 years in the DoD/DoN working on structural components and launch systems, 3 years with a local type 7 SOT, 3.5 years on contract in the middle east as a weapons inspector/Armament mechanic followed by depot level ordnance repair.  Experience that runs the gamut from the lowly individual issue pistol up to crew served, vehicle mounted (including CROWS), some artillery, ordnance components, and even canned sunshine launchers.  Knowledge that spans mechanical, structural, metallurgical, chemical finishing processes, component manufacture, etc.

As we used to jokingly say when I was on contract in the middle east, but I will now say for real: Dude, get on my level.

Edited, never mind: it's not worth it if we have to endure more of your resume or rhetoric down from your soapbox.

Figures.

SO

OP any updates on the rifle?

It sounds like bad mags

I don’t know if anyone mentioned yet but the 10.5 416s have a knob on the gas block. If not you might have to buy the 10.5 gas block online and install it.

Knob?



~Augee

Lulz!

Maybe he means the A5?

We got rid of them. Got a fresh batch of 11.5" DD DI's.

https://www.instagram.com/p/BmbRZ5hgAcL/?hl=en&taken-by=brownellsinc

So what does this mean? Cheap clones, just replacement parts?

Both!

This shit has gotten all retarded.

I'm no expert but it sounds like your bolt is moving too fast.  I dont like to mess with gas blocks, its a pain in the ass when going between can and no can, ammo types, etc.  I picked my most normal ammo (M193) and messed with buffer/spring weights until I was able to slow the gun down to a good speed/reliability balance.

My MR556 likes XP spring + H3 buffer (which even still runs fast with my SDN-6 on it).  My 10.4 was running fast even with HK factory spring and H3.  I suspect you may have blown out the buffer spring when using the very light carbine buffer.

My advice: get a new HK spring / wolff xp spring and H3 or heavier buffer. Slash sells specialty heavy buffers on the EE.  Maybe a $50 solution.

---

Regarding the other convos about HK416s, the USMC per-unit price is around $900 for a bare bones IAR (no optic, buis, bipod, etc.) which is cheaper than our M4 contracts.

Anyone know where I could find a 10 inch vented block at?

I was under the impression that SF cans had more nackpressure than most. Especially the newer tubeless cans.

The peasant ar15 that actually works vs hyped up finicky machine that can barely handle a can, costs to much, is a harsh shooter, et cetera....

I’ll stick with my plebe equipment, thanks.