I've been told not to use an L.I.D. on the SIG MPX since it is a fixed barrel. I was told that the L.I.D. will move laterally. thereby increasing the chance of a baffle strike, or otherwise damage to suppressor. This is pretty much the rule for any fixed barrel gun.

Have you been told something different?

Yes use a fixed spacer or otherwise.

Correct. Here's a YouTube video that was posted today, showing a suppressor run without the fixed spacer.

VSO Gun Channel - I Blew Up My Silencer!

Yea either a fixed spacer in place of the spring or a threaded end that doesn't have the option for either.

I'd personally secure a 3 lug mount to the mpx barrel with rockset and run a 3 lug adapter on the can. That way you can remove it quickly but it has less chance of walking off as thread on suppressors do.

Thats actually what I ended up doing with my mpx. Had tsc cut the barrel to 5 inches and install a 3lug over it.



That's actually a picture of mine with a 45 can on it via 3 lug. It now has a smaller 9mm one.

I watched that after I posted this, I also did an ARFCOM search and found this topic in the Archives. https://www.ar15.com/forums/t_6_20/254289_.html

I put a 3 lug on mine. I felt it was the best solution all the way around. 

direct thread, fixed spacer for mine

3 lug here

I have a three lug adapter on mine. I'd like to get the barrel shortened by 2" and run a better adapter. My Gemtech has not had a problem so far.

AAC TiRant with their 3-lug adapter on mine.

Attached File

You can see my photo from above. TSC machine threaded my barrel and put a mp5 style 3 lug on it(it goes over the barrel so it is rifled to the end). So far it has run without issue.

Can you please post a upclose shot of the muzzle?

Let me start by saying I suck at taking photos. I cleaned it a bit so a bunch of shine is the oil.



Hope those help.

Edit: Mike did offer to do the navy style mp5 adapter where you have the 3 lug and then the barrel threads in front of it with a thread protector. I knew I was going to use it exclusively with 3 lug so went with the non navy version. I originally went in to have him do the sbr engraving for me(I'm local to him). He was looking over the gun playing with it as he hadn't seen one in person yet while I was staring at a few mp5's he just refinished in that burnt bronze. I mentioned that I wanted a sig 4.5 inch barrel but they kept pushing them back and he said he could do it the way in ended up(vs an adapter on the end like most would do). I asked about the refinish and we went outside to look at one of the mp5's in the natural light. He mentioned other colors but that burnt bronze really is something in person. Very happy with how it turned out but that is the norm with him(look at hkpro for a photo thread of his work on far more expensive guns).

I don't remember if it was Mike's idea or his assistant Dale that thought up leaving the top rail black but it really was a good idea. Dale had the idea of painting the inside of the grip. I chose to not have them black fill all of the engraving and just do some of it(helps hide the sbr engraving and a few other dull markings).

As far as barrel length I think the 5 inch is going to be about as long as sigs 4.5 with an adapter on the end of it.

Also along with the shorter octane 9 suppressor I've added a larue trigger(not sure if it was in that photo) and a bcm keymod front grip. Gun is a little picky on ammo as far as blowback goes(runs everything I've tried but like 147gr ammo seems to produce a lot less blowback) but either way is a blast to shoot. Really fun little package.

I like it. It turned out well.

+1 ^ this. I can't find 3 lug adaptors for my legacy AAC EVO 9.