Suppressed M&P Full-sized 9mm not cycling properly

I'm sure this has been discussed here at some point but a search of every combination of 9mm, suppressor, problem, cycling didn't seem to bring up anything for me.
I went to the range today and tried shooting my full-sized M&P 9 with a gemini suppressor. It was a jam-o-matic. I tried several types of ammo with basically the same results each time. The shell case would either not eject or a new round would jam while loading and not go into battery. I removed the suppressor and the gun fired flawlessly. Anybody else have this issue and if so, were you able to resolve it? Thanks in advance for any help that can be provided.

sbmike said:

I'm sure this has been discussed here at some point but a search of every combination of 9mm, suppressor, problem, cycling didn't seem to bring up anything for me.
I went to the range today and tried shooting my full-sized M&P 9 with a gemini suppressor. It was a jam-o-matic. I tried several types of ammo with basically the same results each time. The shell case would either not eject or a new round would jam while loading and not go into battery. I removed the suppressor and the gun fired flawlessly. Anybody else have this issue and if so, were you able to resolve it? Thanks in advance for any help that can be provided.

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That’s why suppressors don’t interest me. You will probably need a recoil spring that’s tuned for suppressors. But that’s way over my head.


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sbmike said:

I'm sure this has been discussed here at some point but a search of every combination of 9mm, suppressor, problem, cycling didn't seem to bring up anything for me.
I went to the range today and tried shooting my full-sized M&P 9 with a gemini suppressor. It was a jam-o-matic. I tried several types of ammo with basically the same results each time. The shell case would either not eject or a new round would jam while loading and not go into battery. I removed the suppressor and the gun fired flawlessly. Anybody else have this issue and if so, were you able to resolve it? Thanks in advance for any help that can be provided.

Click to expand...

Hope this OK to post this. Go to M4Carbine.net Forums and you will get more help than you need.

parsonbw said:

Hope this OK to post this. Go to M4Carbine.net Forums and you will get more help than you need.

Click to expand...

Sorry!! Maybe should not have posted this website. Forgive

Cycling issues are common for folks trying a new suppressor on a gun where it's not been used before. Typically a suppressor reduces recoil a bit and the best solution is to get a lighter recoil spring, or....

You can just order a new spring, for when you aren't using the suppressor, and leave the one in the gun NOW, locked back for a week or so. (Repeat as needed until it's right.)

Keeping the slide locked fully to the rear will likely degrade the spring a little, and that will probably be enough to make it function properly. And the slightly weakened spring will likely let the gun cycle properly with the suppressor not mounted, too.

(This is what is done on some of the forums where shooters use suppressors and lighter-weight springs aren't easily found or are not readily available.)

Lighter ISMI recoil springs for M&P are sold by Brownells, and you need one for the suppressor-equipped M&P.

Thanks for the responses. Since Brownell's hasn't gotten all of my money yet, I'll probably opt for the lighter recoil spring.

sbmike said:

I'm sure this has been discussed here at some point but a search of every combination of 9mm, suppressor, problem, cycling didn't seem to bring up anything for me.
I went to the range today and tried shooting my full-sized M&P 9 with a gemini suppressor. It was a jam-o-matic. I tried several types of ammo with basically the same results each time. The shell case would either not eject or a new round would jam while loading and not go into battery. I removed the suppressor and the gun fired flawlessly. Anybody else have this issue and if so, were you able to resolve it? Thanks in advance for any help that can be provided.

Click to expand...

Does your suppressor have a neilson device (LID, recoil booster) or does it thread straight on?

OKFC05 said:

Lighter ISMI recoil springs for M&P are sold by Brownells, and you need one for the suppressor-equipped M&P.

Click to expand...

I have never changed a recoil spring in my M&P or any other firearm to make it work.

My M&P has been running 100% factory stock for at least a decade now
This M&P must have seven or eight thousand rounds through it suppressed by now.

colt_saa said:

I have never changed a recoil spring in my M&P or any other firearm to make it work.

My M&P has been running 100% factory stock for at least a decade now

This M&P must have seven or eight thousand rounds through it suppressed by now.

Click to expand...

So you are using a recoil booster instead?

OKFC05 said:

So you are using a recoil booster instead?

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Every suppressor that I use on a browning style, tilting barrel, short-recoil operated semi-automatic pistol has a Neilson device/LID
The suppressors that I use on fixed barrel firearms do not have an Neilson device
I can not imagine someone wanting to have to swap recoil springs every time they put a suppressor on their firearm.

colt_saa said:

I have never changed a recoil spring in my M&P or any other firearm to make it work.

My M&P has been running 100% factory stock for at least a decade now

This M&P must have seven or eight thousand rounds through it suppressed by now.

Click to expand...

Mirrors my experience. Close to 1000 rds of 147gr subsonic through my M&P9/Ti-Rant 9/factory recoil spring, with nary a burp. Great host, IMO.