So. As an FYI MCX rattlers have a pinned and welded muzzle device. So the idea of suppressing it, becomes very complicated.

Can’t imagine why they would do that.

I have no idea if some MCX models have a pinned and welded muzzle device and I'm too lazy to research. It would be an odd thing in anything but a 14" barrel for any mfg.
But my local smith charges $65 to remove one and has done one for me (need to change suppressor mount type). Its a trivial job so I wouldn't sweat it too much.

I think the issue is that while it makes some sense to P&W a muzzle device to a 14”-ish barrel to get it to 16” so there are no NFA hassles, it doesn’t make a lot of sense to P&W a muzzle device to a very short barrel that is going to considered a short barrel with or without the muzzle device.

The short barrel Rattlers? Mine wasn't pinned/welded...why would it be?

I don’t think that’s true, the 5.56 models have the fixed muzzle devices that are pinned to the gas block,the 300 blackout do not.

quote:

Originally posted by Andyb:
The short barrel Rattlers? Mine wasn't pinned/welded...why would it be?

Is yours a 300???

The 5.56 is permanently attached. Even says so on Sigs site.

If you look at the specs the tread pattern is listed as none for the 5.56 and 5/8-24 for the 300.

I have heard it is due to the gas system on the 5.56. Though don’t know the actual reason.

Interesting. Mine is 300. What an odd thing to do. I have an LWRC 556 with a 7in barrel and it's threaded. Sig makes some odd choices sometimes.

They have to get the muzzle device on there somehow. No idea how they might do it without threads but OK. So even if its what press fit? shrink fit? pinned? whatever... its an easy gunsmith job to get it off and then thread the barrel. Unless I'm missing something silly about the whole situation. But what's silly is sig in the first place.

Only the 5.56 has the fixed muzzle device. The gas system is part of the assembly.

The only model I see on the sig website that isn't threaded is some 5.5" 5.56 version. And I'm going to suggest that anyone wanting to regularily shoot a 5.5" 5.56 has some real issues beyond the problems of an unthreaded muzzle. I can't even imagine the blast. 10.3 seems awful enough.