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".