[Theohazard]

Originally Posted by odugrad

Just a quick question: would it be possible to use a suppressor on a carbine with a 14.5 pinned/welded muzzle device?

Yes. I have a SilencerCo Saker that mounts to its proprietary Trifecta muzzle device that I had pinned-and-welded to my 14.5" barrel. Most rifle silencers fit to proprietary muzzle devices, and it doesn't make any difference as far as performance is concerned whether that muzzle device is pinned-and-welded or not.

Is your question specifically about attaching a silencer to a rifle with a factory pin-and-weld job that uses an A2-style muzzle device? For that you'd need one of the few rifle silencers that attaches to the standard A2 muzzle device (or a similar design). There are several companies who make them. Keep in mind that these kinds of silencers usually have less-convenient mounts and are usually over-bored to compensate from misalignment that can arise from muzzle devices that are machined poorly or mounted using a crush washer. So these silencers tend to be louder than ones that are designed to attach to proprietary muzzle devices.

Also, keep in mind that a regular A2 flash hider isn't long enough to make a 14.5" barrel reach the legal 16" minimum, so companies that sell 14.5" pinned-and-welded rifles need to use a non-standard muzzle device that is longer than the A2 flash hider. So a silencer designed to attach to an A2 flash hider might not work with some of these longer muzzle devices.

Originally Posted by odugrad

I've heard that you have to remove the crush washer from the muzzle device to use a suppressor.

That's correct. It's not a good idea to mount a silencer to a muzzle device that's been timed using a crush washer. The crush washer crushes unevenly so the muzzle device is often misaligned slightly. Attaching a silencer to a muzzle device that was mounted using a crush washer can cause baffle strikes.

Companies that make silencers that are designed to attach to A2-style muzzle devices tell you to remove the crush washer and re-time your muzzle device using shims. That said, these silencers are often over-bored enough that you might get away with using a crush washer, but it's not a good idea.

If you have a rifle with a pinned-and-welded muzzle device, a competent gunsmith can remove it and pin-and-weld a new muzzle device that will match the silencer you have.

Originally Posted by Mobuck

Not sure why a crush washer is used with a "pinned and welded muzzle device

It's very common. Daniel Defense, PWS, BCM, and many others all use crush washers to time their pinned-and-welded muzzle devices on their 14.5" barrels.

Originally Posted by Mobuck

I have only seen ONE suppressor mount that used a collet clamped onto a common flash hider and the user said it was very expensive.

Sure, those types of rifle silencers are in the minority, but there are several companies who make them and they're not typically any more expensive than silencers that use proprietary muzzle devices. Knights makes one, Gemtech makes a few, and Griffin makes several. There are probably others that I can't think of off the top of my head. In fact, the various Gemtech Halo and Griffin M4SD models are priced in the mid-range as far as brand name 5.56 silencers go.

My guess is the silencer you saw was a Knights NT4; they're expensive, but that's because they're sold by Knights, not because they're designed to attach to a standard flash hider.