Just got my Gen 2 MPX barrel chopped from 8" to 6" and re-threaded to work with my suppressor.

Took it to the range today and it choked/jammed on every kind of supersonic and subsonic ammo I tried to run through it (unsuppressed). It ran 100% suppressed, however, except it would not lock back on an empty chamber using subsonics.

I assume I will need to "open up the gas port" to the Gen I specs to run unsuppressed? The place I had the barrel cut/threaded did not offer this service. I'm pretty handy and have successfully built a number of 1911s and AR's so I do not believe that doing this myself is beyond my grasp, but I'm not finding anything on how to do it out there in internet land.

Anyone have any info/experience with this?

Like you I want to try myself, but I'm afraid to attempt without a mill. I know it will take a .055-.059 carbide or stronger bit and super slow mill. Taking the barrel and gas block apart is not that big of deal as I have already switched my 8" barrel to a 4.5" barrel from ILWT. And both ILWT and Taylor Pickell on the MPX group on Facebook are opening ports up on the Gen2's.

That is about all the info on this I know of, but if you do attempt it yourself or whatever your route, please keep us updated for the ones who are following this stuff.

Odd. I've been using a gen 2 cut down to 4.5 with no issues super and subsonic and suppressed and non. Wonder if they changed the gas specs at some point during gen 2 production.

Gen 2 gas ports are around .045 and I think Gen 1 gas ports are opened up around .060. from what I understand on Gen 2 it is hit or miss on gen 2 cycling issues. So far mine will shoot anything but 165gr Hush ammo. And according to Sig, they said they do not recommend Hush ammo at all, at least that is what I was told when I called them and said my Gen 2 will not cycle 165gr Hush ammo. So, I ordered some 147gr Hush ammo to give it a try, because I know mine will cycle 147gr AE ammo with no issues.

Send it to Taylor Pickerell.

I decided to have a go at this myself. Once you get gas block off the barrel it's pretty obvious what to do. I tried using a #53 HSS drill bit but the steel is too hard for that. Ordered a carbide bit and that should do the trick.

We'll see what happens with the carbide bit, but I'd say if you have the right tool, it should not be a big deal to do this. I just can't see paying someone $75 to open up two holes if I can do the same thing for the price of a $10 drill bit.

Let me know how it goes!

Well, mission accomplished, apparently. I ordered this bit:

#53 Carbide Bit

which opened up the gas port to .059. I actually just used a cordless drill on low speed, using plenty of oil with the barrel and gas block in a vice. It's pretty apparent once the gas block is off the barrel which ports you're opening up. The one in the top of the barrel, obviously, and the corresponding port in the gas block which is directly over the hole in the barrel.

I only got to test it with a few rounds, but my hand load 147 grain rounds that are right around 1000 fps locked the bolt back on an empty mag, which they have never done before. That was with the suppressor attached. The real test will be how it runs without the extra back pressure produced by the suppressor. I'll update once I get a chance to shoot more. BTW, if anybody wants to give this a shot, I'll send you the bit. Only been used for those two holes and I don't see ever using it again. Here's a pic, just for fun.

Attached File

Sweet! Glad it worked out for you! Like you, I didn't think it would be that hard with the right bit, I was just afraid to try it without a mill, I actually thought about buying a small drill press that runs slow and giving it a try.

I'm waiting now on an order from freedom munitions of Hush 165gr and Hush 145gr along with my Form 4 being approved at anytime (I hope) went pending June 15 2016 to do some testing on my own without having to bug my buddy that has a pistol suppressor and is always on a time limit, so I can really spend time at the range shooting different ammo. I know mine will cycle 115gr, 124gr, and 147gr of other name brand ammo. But when I try 1 or 2 rounds of his Hush ammo, it will not cycle at all. So, I may go ahead and order me a bit and get ready to do it myself, I really enjoy doing my own work on all my firearms, from cerakoting, threading barrel on my 300wm, fitting threaded barrel and trigger in my 1911 and fitting a threaded barrel in my Para Ordance Pro Custom 18.9 so, surely I can drill 2 small holes :)

Thanks for the update!