Suppressor question

[RCCrawler]

So I got my first suppressor last week and have been messing around with it as I can. I picked up the SWR Spectre II, it is said to reduce noise by 41 decibels. The only firearm I have right now that I can put it on is my Sig 1911-22. When Shooting it suppressed vs. unsuppressed I would say the noise is decreased by 90% I was actually very impressed.

Yesterday we went out again and shot it on my dads S&W 15-22 rifle, I figured being a rifle it would be a lot quieter than on the pistol as rifles are naturally quieter to begin with. The difference on the rifle between suppressed and unsuppressed was maybe only 10% if that.

What doesn't make sense to me is unsuppressed the pistol is way louder than the rifle, then using the same suppressor the pistol is way quieter than the rifle.

Being my first suppressor I am very new to this, are these results typical or is something strange going on here?

BTW the same ammo was used in all testing.

[Sharpienads]

Maybe it has something to do with barrel length?

I have no idea.

[hatidua]

Just a guess: IF, the ammo was supersonic ammo, it would likely not reach full speed in the shorter pistol barrel (would remain subsonic), whereas the longer barrel would allow the ammo to reach full supersonic speed. Supersonic ammo, no matter which suppressor, is going to emit that sonic crack.

Another thing you'll likely find: after you clean the suppressor (50/50 mix of vinegar and hydrogen peroxide works well on those stainless baffles), you'll likely find that the first 10 shots are a bit louder than those after that - a slightly dirty set of baffles in the Spectre/Spectre-II (and very likely every other can out there) actually absorbs sound better than sparkling clean baffles.

I only shoot subsonic ammo and with the Spectre-II I don't notice much difference in sound between a rifle & pistol, both are relatively quiet. Every so often, an inconsistent ammo (like Federal 711B that is supposed to be subsonic) will have a supersonic round in the batch and it's night/day difference between the two, -there's absolutely no mistaking a 'fast' one in the box.

If you were using truly subsonic ammo, the action noise would be the only significant difference in sound between the two firearms.

[RCCrawler]

Just a guess: IF, the ammo was supersonic ammo, it would likely not reach full speed in the shorter pistol barrel (would remain subsonic), whereas the longer barrel would allow the ammo to reach full supersonic speed.

That makes sense there, we were using supersonic.

Another thing you'll likely find: after you clean the suppressor (50/50 mix of vinegar and hydrogen peroxide works well on those stainless baffles), you'll likely find that the first 10 shots are a bit louder than those after that - a slightly dirty set of baffles in the Spectre/Spectre-II (and very likely every other can out there) actually absorbs sound better than sparkling clean baffles.

Yea that wasn't the case here, we kept switching it back and forth with no cleanings in between.

I only shoot subsonic ammo and with the Spectre-II I don't notice much difference in sound between a rifle & pistol, both are relatively quiet. Every so often, an inconsistent ammo (like Federal 711B that is supposed to be subsonic) will have a supersonic round in the batch and it's night/day difference between the two, -there's absolutely no mistaking a 'fast' one in the box.

Yea we noticed that as well, every now and then you'd get a live one.

[Circuits]

Supersonic ammo still makes noise passing through the air - called a sonic boom.

Apparently, out of a pistol barrel, the round stays subsonic, so the suppressor nicely eliminates 90% of the muzzle report, which is 90% of all the noise.

Out of a 16" rifle barrel, the round is supersonic, so the suppressor eliminates 90% of the muzzle noise, which is apparently less than half of the total noise. Ditto what hatidua said about "first round pop" which is a phenomemon associated with a cold, empty suppressor. Once the can heats up, and/or has fluids introduced to help with cooling expansion gases, suppressor performance gets much better.

[RCCrawler]

I'm curious to hear what it sounds like out of my S&W 15-22 once I cut it down to 8".

[SAnd]

after you clean the suppressor (50/50 mix of vinegar and hydrogen peroxide works well on those stainless baffles), ...

I've been warned that the residue left over from the vinegar/hydrogen peroxide mix is extremely toxic. It forms lead acetate which will pass lead through your skin. Be sure to wear the proper rubber gloves and other appropriate protection. You should also make sure you dispose of it properly.

All the descriptions of 'The Dip' said to use white vinegar. I don't know if it makes a difference.

Have Fun

One other bit of information for what it's worth. Just about every thing I have heard and read says the Magic Length on barrels is 4.5 inches. High velocity ammunition will not go supersonic on any barrel not longer than 4.5 inches. In my limited experience that has been true. I have shot a couple 22rf 1911's using high velocity ammo and they mostly stayed subsonic. They had 5 inch barrels. All the other short barrels I shot were 4.5 or less and none of them went supersonic. That's with normal high velocity, not the super hyper velocity ammo. I haven't tried that.

Test fire several rounds without the suppressor if you do play around with short barrels. Look for any signs of keyholeing. I have a Beretta 21 that is sensitive to the ammo I feed it, some ammo keyholes. You do not want any bullets to tumble inside you suppressor.

[Schrambo]

4.5" AR barrel, Spectre II, Slidefire stock, 50rd mag... SS ammo...

Nothing but a little action noise, louder giggles, and tinkling brass...