Good day everyone!

I have a Gemtech Outback silencer that has the same thread

as the 15-22. It is marked for .22LR. It works fine on my Beretta

.22LR 22-A pistol.

When tried on the 15-22, it threads perfectly and seems to line up

in every way.

Here's the question: There is no silencer effect whatsoever while

mounted on the 15-22. It does fine on the 22-A Beretta.

I hope this doesn't sound numb, but am I missing something?

What ammo are you using? If you are using high velocity ammo, you are hearing the bullet breaking the sound barrier. In a rifle length barrel you need to use standard velocity or subsonic ammo. In a shorter pistol barrel (4.5" or shorter) high velocity ammo will not reach super sonic speeds and will not (most of the time) break the sound barrier...

Also the threads on your M&P 15-22 barrel are too long for most suppressors - I do not know about the Gem Tech Outback, but YHM and Silencer Co suppressors require a spacer to distance your blast baffle a specific distance from the end of the muzzle - your problem could be related to this as well... Measure the threads on you pistol and on your rifle and compare them - I would be willing to bet that your pistol will be .2" shorter...

Ammo is key in that length barrel.

The previous posters are correct. You will need either standard velocity or sub-sonic ammo in your rifles. It will also work better with the spacer. You can find the spacers on some of the suppressor companies websites. With the Beretta, the short barrel allows the use of high velocity ammo.
Even with the correct ammo, the action on the 15/22s is pretty loud. I wish there were some baffles that would make the action quieter.

__________________
Rick
SWCA #2396

Suggest CCI Standard Velocity. Dick's Sporting Goods $25/500. Dunns is selling 5K for $270 delivered.

I'm stopping at dicks on my way out.

I am running a Kodiak TL suppressor on my MOE and had ran 100 rnds of Remington standard velocity and it was transonic but very quiet at the ear. You need a .300 x .700 thick spacer and if you want you can add a small oring and heavier recoil springs to the bolt group and it will help with action noise. Everything else that 10mm said is right on the nose.

This is why I'm glad I joined and read this forum. Every now and then I run across a post like this where I learn 4 or 5 things in such a short post! Thanks 10mm Shooter.

You guys are the greatest!!!

Thanks so much, I will get the correct spacers and report back.

Oh, yea, I was using Federal Bulk, make a difference?

Federal bulk is not standard velocity ammo, you want 1000 fps, federal is 1300 fps I believe.

fed bulk is 1260. but thanks again, I'll make sure I try standard

vel. when the spacers come in.

Funny how this all comes together for a person when you're

reminded of the lengths, and basic construction of the baffles.

Always learning something here...thanks again, will report when

spacers are here.

Regards brothers

I shoot the YHM mite and use CCI subsonic out of everything except the Walther p-22 wich stays subsonic with all ammo. Rule of thumb is about 4.5 inches or less barrel length will stay subsonic with bulk ammo anything longer will need subsonic to avoid the "crack" from my expierence.

Now Im not claiming to be wrong or right but I dont think a washer/spacer is going to make a noticable difference with the sound. Ill test it, but I dont use the washers. My can threads on fine on the rifle and pistol BTW. Gemtech may be different.

I may be wrong, but I thought the spacer was used to not over pressure the blast baffle and to help with not bottoming out/ messing up w/ anything else?

If the barrel is extending up into the blast chamber that is part of the problem.

As regards ammo selection I have found CCI Standard Velocity to be a great performer in suppressed .22 rifles and pistols.

Let me ditto what Porkchop said.
I Finally received my stamp and picked up my Outback IID the other week. So far I have only had a chance to run a few rounds through the Sig Mosquito to test it out. Next week I was hoping to get a chance to take the family of M&P 15-22's for a test run with it. I never knew about the spacer until now. Just ordered three of them.
Thanks guys.

As for the technical explanation: I think straight from Gemtech says it best

"Most .22lr silencers have female threads that run around .400 deep, which works on most threaded .22lr firearms. However, if you put these silencers on .22lr conversion kits used on AR15 / M4 type barrels, those 5.56mm carbines are threaded much longer.

This precision-made threaded spacer allows you to use a .22lr silencer on longer thread length barrels. It creates a firm, large shoulder for the suppressor to butt up against, filling the gap that would otherwise be left. It also prevents the extra length of male barrel threads from protruding into the silencer's blast chamber -- where carbon and lead can build up on these exposed threads making it hard to remove the silencer. This GEMTECH spacer is all you need to make the pieces fit on most any .22lr AR-type type carbine (including the S&W M&P 15-22, which has long, 5.56mm AR-spec threads) and most any .22lr silencers. The spacer threads onto your barrel, and may be installed with adhesive for a semi-permanent solution. Durable steel with wrench flats for removal and assembly, in a blued-black finish."

now it makes sense thanks. The YHM is built differently. Definatley dont want the barrel screwing into the can, you wouldnt get use of all its volume thus being possibly louder.

I just recieved the Gemtech spacer for .22LR threads for silencers.

The spacer and the use of CCI Standard Velocity did the trick!!!

Nothing but bolt sounds!!!!

Thanks for all the help.

Regards.

If 1,000 fps is the threshold for the sonic crack, how does a larger caliber suppressor work differently than a 22lr? I don't know anything about suppressors so if that's a dumb question, I appologize in advance.

Regards,
Frank

Caliber does not matter when it deals with suppression of a firearm. There are two separate sounds to deal with (1) being the sound of the weapon being fired and (2) the sound of the bullet breaking the sound barrier (sonic crack).

A suppressor only deals with the sound of the weapon being fired. To deal with the sound of the bullet breaking the sound barrier one has to use ammo that is subsonic (generally less than 1100 feet per second). There are several other factors that are in play as well (1) barrel length and (2) ambient temperature.

Most common factory rifle ammo is designed to reach maximum velocity when used in a longer barrel such as 16", but when used in a shorter barrel, it will not reach its maximum velocity. When shot out of a 4" pistol, most factory 22lr ammo will not break the sound barrier.

Temperature also affects this as well. Warm days are your friend when trying to keep a bullet from breaking the sound barrier. On a real cold day, even a subsonic round can break the sound barrier and you will hear a sonic crack.

When suppressing a larger caliber rifle such as a .223 or .308, a suppressor only deals with the sound of the weapon being fired and you will still hear the sonic crack the bullet makes when it breaks the sound barrier. One can load subsonic rounds for any weapon, but weapon performance is usually diminished to the point of being useless. With this there are some larger caliber rounds that work well with a suppressor - an example would be the 300 Blackout round...

And Frank - the only dumb question is the question that does not get asked...

Thanks for the education, 10mm. I appreciate you taking the time to explain.

I've been reading old threads trying to learn what I can before taking the plunge. Right now I have more questions than answers.

I'll keep reading, hopefully some of the threads will answer them.

Regards,
Frank