Sig MPX Mod Help Please

[Blitzen]

Asking for some pointers on installing a Rugged 3-Lug adapter on a Sig MPX pistol with the 4.5" barrel and fake suppressor. Appears to be one screw underneath that holds the hand guard in place and upon removal I assume the hand guard will then slide forward and off. Am I missing anything on the hand guard removal? Next will the fake suppressor be hard to remove? Hopefully no factory thread compound was used etc. Also appears there is only about 1" of space where the barrel could be put in a vice so that is an issue. Rugged recommends red Loctite with 20-25 ft-lbs of torque. Wonder if Rocksett would be better choice due to it's temperature rating. Any pointers would be appreciated before I get into this.

Edited April 7, 2020 by Blitzen
Update information

[Magiccarpetrides]

I’d recommend you reach out to xtriggerman on here he seems to be the resident firearm magician if he doesn’t know the right answer I’m sure he could figure it out quick.  

[Trekbike]

On 4/6/2020 at 8:46 PM, Blitzen said:

Wonder if Rocksett would be better choice due to it's temperature rating. Any pointers would be appreciated before I get into this.

If you already have some on hand, I'd use Rocksett as my first choice over Loctite.

[Blitzen]

42 minutes ago, Trekbike said:

If you already have some on hand, I'd use Rocksett as my first choice over Loctite.

I was thinking the same thing. Contacted Rugged about switching to Rocksett. No problem. Not sure why they would recommend Loctite due to it's lower temperature rating. The barrel is 4.5"s so the adapter I think would easily exceed red Loctite rating. Trying to figure out how to hold the upper or barrel assembly to get the faux suppressor to move. It's on pretty tight. Can't find anything specific on the web. Might be better to take it to a local gunsmith who is experienced. Thanks for the replies. 

[Trekbike]

19 minutes ago, Blitzen said:

Trying to figure out how to hold the upper or barrel assembly to get the faux suppressor to move. 

Strap wrenches?   

[TomInMN]

34 minutes ago, Blitzen said:

Trying to figure out how to hold the upper or barrel assembly to get the faux suppressor to move. It's on pretty tight.

If it's for sure going to be thrown away, might be easier to hold the can and rotate the upper assembly.

[Magiccarpetrides]

I would definitely get a gunsmith to help...last time I tried to force something that shouldn't have been forced I ended up having to send my gun off to fix my screwup.

[ken_mays]

The handguard should be retained by the front pivot pin that holds the receivers together.   Take off the upper and the handguard should slide right off.

 

As to flash hider removal, it looks like you can put the receiver into a vise where the barrel meets the trunnion.  It's flat there and nothing really protrudes.  I would pad it with leather and be gentle on the vise handle.   Put the receiver in the vise upside down to prevent crushing the port cover tube. 

There will probably be a flat on the tube somewhere you can get a crescent wrench on.   If not, grab more leather (old belts are handy) wrap around the tube near the receiver end, and use a pair of slip joint pliers to work the tube off.   If it isn't budging, hit it with a propane torch for 30 seconds or so and try again.

[Blitzen]

Thanks for replies. Talked to Rob at In Lead We Trust. Very helpful. Best to remove barrel assembly. Then assembly can be put in a vise. Could warp the MPX receiver if too much pressure is needed to remove muzzle attachment which could cause mis-feeds. Purchased a ILWT mag well vise block to aid in gun maintenance and barrel assembly removal. Remove the two barrel screws and it should slide out.  Like mentioned by ken_mays I may put some heat on the faux suppressor. 

[TomInMN]

@Blitzen how'd it go?

[Blitzen]

Job done. Removed barrel which on MPX is simple. Mounted barrel in the vise with padding. Heated faux suppressor flats with a torch for a few minutes. Broke free without having to use very much force. My guess it was tightened to around 25 to 30 ft-lbs and no thread locker was used. Mounted 3 Lug adapter with 1.5 drops of Rocksett and torqued to approximately 20 Ft-lbs. Not a lot of threads on the barrel.  Had to work the In Lead We Trust flash can 3 Lug mount a little to get it to properly mount. According to ILWT the mount is made to exact HK specs and if a 3 lug is even a half thousand off it could be a tight fit. Anyway both the flash can and obsidian mount up snug and tight. Used a Rugged Suppressor 3 Lug adapter. It has flats which was a plus.