Yesterday I had an opportunity to use my Sandman "K" suppressor on the 9" barreled Galil Ace 556 that I SBR'd a few months ago. Tried it out indoors and as expected there was still plenty of flash and noise, but the level of blast did seem to be mitigated somewhat. When my buddy fired his ported .38 Super handgun afterwards, it seemed even worse. Realistically, I guess mitigation was all I could hope for.

I'll be using this device on a couple of 16" barreled 5.56 ARs and my Tavor X95 in .300 BLK too. I went with the Sandman "K" in part because I wanted to keep the OAL as short as possible and going with a longer suppressor didn't seem to be heading in that direction. Am I missing anything here? I'm still new at this suppressor thing and it presents a number of conundrums.

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Originally posted by pulicords: Am I missing anything here? I'm still new at this suppressor thing and it presents a number of conundrums.

I stayed at a Holiday Inn Express last nigh, so take the following with a grain of salt. From what I have gleaned, the shorter the barrel you go with, the more benefit you gain with a longer suppressor. "K" suppressors seem to be most effective on the 14.5" to 16" barrels, as the full size cans will almost always be net quieter on the 14.5/16" barrels. But the result at your ear may not be significant to offset the increased weight/length (ie reduced maneuverability).

The issue with the Sandman-K can is half the can length is for the Keymo adaptor. Leaving only a blast chamber and ~2 baffles. So more suppression than a blast deflector muzzle device, but not as close that of a full size can as you may expect. On the shorter barrels the full size can allows more of the powder to burn before exiting, while the shorter barrels less so. On the longer barrels (14.5/16) this is less of an issue which allows the can to deal more with the pressure change than both the pressure/unburnt powder. Leading to a less significant difference in performance between a full size can and a K.

Also, the Galil Aces tend to be overgassed which may also be effecting how quickly the bolt unlocks and allows pressure/sound back down the barrel closer to the shooter's ear. You may want to purchase a KNS piston as well to reduce said pressure, if you will be using the Galil suppressed more often than not.

all the short ones suffer in material ways. Its just that simple. There is no magic design parameter. You are trading length (and weight) for way less of everything else. And volume is in the end the cornerstone of success. Some of mine offer the option to reduce the size and I can say I never, never do it. the reason I want it suppressed is guess what? actual suppression.
Get something longer/bigger and you will be happier.

I understand the appeal of keeping the small gun small, but, as both Vgex and hrcjon already pointed out, it doesn't make for the best setup, in regards to sound suppression, for all the reasons they mentioned. As with everything else, it depends on your intended application; if you're wanting the smallest version of that particular gun, with just enough suppression to "take the edge off", then the K can will work for you. "The edge" is subjective, and, for me, a K on a shorty 5.56 doesn't cut it. The 553 is an almost perfect comparison to your Galil; I have found a Griffin M4SDK to be unsatisfactory on that weapon, and that's a larger K can than most. There is perhaps a point of diminishing returns, when it comes to barrel length and the size of the silencer necessary to adequately suppress the report: if a nine inch barrel needs a nine inch silencer to perform the same (sound-wise) as a thirteen inch barrel with a five inch silencer, you may as well go for the extra barrel length. In my experience, the extra weight and length of a can virtually disappears, when shooting the gun; if you're toting it around for extended periods, you'll notice both; if you're just looking at the gun, the length may seem unappealing on a short-barreled weapon. As a final note, it seems a DI always suppresses better than a piston, in terms of sound, which as hrcjon points out, is the bottom line.

A sort of case in point: I have a 10" DI AR with a direct-thread YHM TurboK; it's overall barrel length is ~14.5". The 9" 553 with the Griffin M4SDK on a Smith Vortex brings that overall barrel length to ~14.5". The AR is far nicer to shoot, and it's not because the YHM is a better can.

Thanks all for the input! After doing a bit more research, I've got a Keymount 5.56 flash hider and a 1.5" Sandman E-brake on the way to add to the Sandman K, as well as a couple of compatible flash suppressors for other rifles. I believe this will result in reduced flash when used with the Galil SBR, while also allowing me to use this system on a couple of other 16" (DI) ARs that I own. If I want a greater level of suppression, I'll have that option with the longer barreled guns.

Since my Tavor X95 is already set up for the Sandman "K", so long as I'm careful to replace the 5.56 flash hider with the OEM .30 caliber end cap, I'll also have that option. Using subsonic ammo, this will be about as quiet as I'd want.

I bought a Sandman K specifically for use on a 300Blk SBR. I’ve only shot it at the range (had to wear hear pro obviously cause of others) but the “tone” and noise level wasn’t bad. My main purpose for it was to keep my ears from bleeding if I used the gun in a self defense scenario indoors. I totally realize your 5.56 SBR is another animal though.