I think this is the article...

https://smallarmsreview.com/the-hk21e-machine-gun/

We like to have beef with companies like HK and KAC, but I think they've done some awesome stuff in the realm of small arms development, in the 80s, 90s, and into the 21st century. They just don't seem to care much about the commercial side of the industry, so they catch hell for limited availability and high prices.

I've been lucky enough to get some time behind a few belt-fed guns, the HK21E being one of them. The HK really is a superb gun. It oozes quality and ruggedness. It's two machine guns in one, 5.56 and 7.62, what's not to love? It is a bit heavy, in 5.56 configuration, when compared to things like the M249 or MK46, but it's arguably much better. The closed bolt operation may be a point of controversy, but the linked article has something to say about it: "The HK21E provides a cook-off rate in excess of 1,000 rounds (cyclic), a fact proven by extensive testing, despite some claims that this is impossible from a closed-bolt design like the HK21E."

Man, just skimming through that article again is awesome. It was published originally in 1998; when gun writers weren't always shills, and when gun makers like HK were pushing the envelope.

To make the drift less significant: I have been lucky enough to shoot one of these because a friend has one; a friend who I hope to convince to put a silencer on the thing one day.

This message has been edited. Last edited by: KSGM,

To return to the OP intent...

Did some shooting at night recently, as described in the night vision thread. The flash was the only ting to aim at. I was reminded of things I had read about Vietnam; how the dense jungle often made the flash your only good indicator of the enemy's location.

What a humongous advantage a silencer affords, in the flash reduction (and even elimination) aspect.

In some tinkering last night, I noticed that, in comparing a SF 556 mini and RC2, on the same gun with the same ammo, the RC2 didn't have any noticeable reduction in flash. I thought the larger silencer would surely have better flash performance. It seems flash reduction is inherent to the design of a silencer, itself, and not necessarily related to internal volume. I'd venture a guess that an excessively long silencer would have better performance, but then you're talking about length/weight tradeoffs that aren't worth it.

Did some looking and listening last night. With the help of a friend, I ran through six silencers on the same host. I had a reaction rod in a vise on a toolbox in the bed of the Jeep, which allowed me to swap devices as needed.

Six rounds per can. Three fired by each man, with the non-firer being an observer. After each silencer, we compared thoughts, and I jotted down notes. Ammo was factory Hornady 73gr FTX Critical Defense.

Both men were using PVS14s. Shooting was done passively, to avoid emitting other signatures. We did take note of a potential discrepancy in flash impressions, due to the NVGs being different. Mine is a Gen3 green tube of unknown manufacture date; buddy's is a Gen3WP tube that was likely made after 2020.

This list represents the silencers looked-at, in the order they were shot:

Otter Creek OCM5 - Quiet and very small flash. The flash could be described as a small dot, surrounded by a baseball-sized orb, with about a 12" streak protruding from it. This is the can I have been using lately, and served as the baseline to which the others were compared.

Suefire RC2 - Noticeably louder. Flash negligibly larger.

YHM TurboK - In between the first two, for noise. Flash noticeably larger.

Gemtech GMT HALO - Friend thought it was louder as the viewer; same noise as the shooter. Flash was the same as the TurboK.

Gemtech HALO - Quiet. I thought this silencer had less flash than the first two; friend thought it was the same. This prompted the hypothesis that our viewing experiences differed slightly.

Griffin M4SDk - Noise was a hybrid of the RC2 and TurboK. Flash was the same as the TurboK and GMT.

I was surprised by the performance of the steel HALO. I've had that can a while, and it's had a lot of rounds through it. It's arguably old tech. The sound and flash reduction are awesome. It's weight is a big demerit though. It weighs about 24oz; that's ~9oz more than the OCM5. The extra weight is not worth the (potentially) better performance.

I thought the M4SDk was going to be the surprise performer. I was definitely wrong.

I am going to stay the course, with the OCM5.

Respect is due to the Surefire as well; it's the loudest of the bunch, but it's a well-rounded performer. They do tout "TSR".

The TurboK and M4SDK are indeed "K" cans, which no doubt didn't help their odds.

This message has been edited. Last edited by: KSGM,

I am interested in the CAT WB inconel silencer. These demonstrations of flash performance don't help. The sacrifice made with titanium is plainly demonstrated here.



This intro gave me a chuckle...

quote:

Originally posted by KSGM:
The sacrifice made with titanium is plainly demonstrated here.

This whole “signature” topic has become very interesting to me.

I have one suppressor for some of my bolt guns and I can’t even imagine wanting anything more unless the sudden apparition of Our Lady of Perpetual Silence results in silencers being taken off the NFA, and probably not even then. In addition, as one commentator in a video pointed out, if all someone is using a can for is just to reduce the amount of hearing protection necessary at the range (or to impress the other shooters) or even for use in a semiserious pursuit like hunting, then signatures don’t matter.

But if someone owns a can for not only a more pleasant daytime plinking experience, but also with even a vague thought of, “If X happens, it would be a good feature for Y,” then I wonder how many people are even aware of different signatures, much less worry about them. Seeing the sparking that often occurs with titanium suppressors was a real eye-opener for me, and not something I would have suspected if you hadn’t mentioned it here.

Your exploration of the topic, including personal experiments, are examples of what anyone who might imagine using a can for truly serious purposes should be doing, but I suspect it’s pretty rare.

Yeah, titanium cans are being called "sparky bois" in other places online. It's a thing.

But what you have to know is if what you are seeing is a 'new' can where it can be really really bad due to ti mfg. debris or one that has a number of rounds (the suggested minimum I've heard is 200) and then you can get an idea of the baseline. But for sure you don't want a ti can if flash is your priority.

quote:

if what you are seeing is a 'new' can where it can be really really bad due to ti mfg. debris

Fair point.

In this video they show their suppressors night signature.

https://www.absuppressor.com/a-10

And another cold weather shot.

A friend has a transferrable lower. The same friend has a 7" RRA upper. This friend wanted to make noise, and invited me to participate.

I contributed a mag to the effort. My mag was loaded with 55gr PMC XTAC. His were loaded with something Winchester; details were unknown to him.

That thing spat HUGE fireballs with that Winchester ammo. About what you'd expect, considering the rifle: at least two-foot-long fireballs of a bright white/yellow, with even the slightest hint of green. My mag of XTAC, however, had almost NO flash. It was very impressive. There was an ever-so-slight lick of flame on every shot, but it was no more than I'd expect to see out of anything under 14.5", I suppose.

There was no silencer in play here, but the moral of the story is that the (overwhelming?) majority of the visible signature equation is ammo-related. You can't even begin to objectively consider the flash or smoke signature of any given rifle, muzzle device, or silencer if the ammo being used isn't a proven performer.