How to use a .40 S&W (or .45 ACP) suppressor on a 9mm

“Hey, I have this .45 ACP suppressor and I want to put in on my 9mm gun, how do I do that?” It’s actually a lot easier than you think, and in today’s tech post we’re going to explain how. The first thing you have to understand is that your .45 barrel and your 9mm barrel are definitely threaded to different pitches.

The good news is that a .45 ACP suppressor or a .40 S&W suppressor will work with a 9mm, although it might not give you the same level of decibel reduction that you’d see from a dedicated 9mm can. But because of the different barrel threads, you’re going to need to make some modifications. You can’t just screw your .40 can on a 9mm barrel. The process for doing this is pretty easy though.

Your pistol suppressor has a part called the piston – this is the part of your suppressor that threads on to the barrel of your pistol. Certain suppressors, such as the Ghost from Dead Air have multiple different piston options that you can select when you purchase the suppressor. So for example, if you initially buy your can for a .45 ACP and have your barrel threaded to the appropriate .578×28 but later want to change to 10mm, you’ll need to buy a separate piston for your suppressor to allow that.

Image from Dead Air Silencers

There are other issues that can pop up as well. In the example used above, .45 ACP and 10mm, .45 ACP barrels are threaded at the aforementioned .578×28, whereas 10mm barrels are threaded in 9/16×24. Unfortunately, you can’t just cut a 10mm barrel with .578×28 threads, because there isn’t enough meat on the barrel to accommodate the deeper threading a .45 ACP can requires.

So if you’re looking to minimize costs and only buy one suppressor for multiple pistols, the best choice is to get a multi-caliber suppressor that allows you to change the piston. Then you’ll be able to go from .45 ACP to 9mm, or .40 S&W to .45 ACP, swapping the can back and forth between guns to your heart’s content.

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