MrRick

I went with the MPX. After a lot of back and forth shooting CZ, AR9s and avoiding to look at the MPX (because of price) I went with it after shooting it. Seen a few guys at my local matches break a few magazines on the CZ so that also kept me away from it. I had one issue with mine and Sig took care of it right away and sent me a new part under warranty (regulator valve). I dropped a CMC trigger and found after 2000 rounds that the hammer was mushrooming. So I dropped a Gesseile SSA-E and so far doing good. I kept thing simple with the MPX. With the MPX magazines, if you cut the magazine restrictor you can get 4-5 more rounds in the magazines. I was concerned with the stock being on the short side but I like it because it allows me to shoot with ear muffs no problem. I did my first match with it last Saturday and it ran flawlessly. Even the stock was fine. I have shot all kind of different bullet weights (factory and reloads), all different powders and I found that 124s gave me the less dot movement. Right now using Autocomp at midrange but I like Titegroup better. If I was to change anything on it, it would be to put an Eotech red dot. I'm using a Vortex Sparc AR and it is fine but I want a larger viewing window.

Well I'm going to stick with the original hammer and I'm going to try out the Bull Moose tactical flat face trigger and see how that works with the factory hammer. It also comes with a lighter trigger spring.

I also noticed that when I looked it over. The hammer is a bit on the short side. I'm just going to stick with the original trigger system for now. Debating if I want to put JP springs in it though.

Thanks Eric. Really appreciate it

Hammer pin holes are fine. The CMC hammer width is almost the same as the firing pin hole crevasse. Don't think it is a hardness issue since the BCG is also getting beaten up. Both of my CMC trigger are the same width. Would like to find an aftermarket trigger that is wider and or taller but not holding my breath.

Mushrooming

For those using CMC triggers in your MPX. I noticed the hammer on the CMC trigger group to start mushrooming and the area around the firing pin was getting beaten up pretty good. Factory trigger and MIL SPEC triggers are .300" and the CMC is .215 wide. I have about 2000 rounds through it with the CMC trigger and this is a Gen 2. What are the width of other aftermarket triggers?

I asked this guy a while back and he said he could do it. I came across him from a lot of good recommendations from here and other local shooters. http://jandlgunsmithing.com/

Will look around the shop to see if I have any (my guys like to grab them). If not, next time we expend some ordnance, I just send it to you. No fee. Mine is sort of wrinkled from being in my bag.

My Gen 2 does have one. Try a pen spring?

I put a CMC flat trigger on mine. 1300 round no problems with it.

Looking for a starting point for those 2 powders with 135gr. Would like to use the Titegroup in my Tanfoglio and HS-6 in my MPX.

I load Xtreme 147s in various CZ/Tanfoglio. My P09 being the most picky. Requires me to load the shortest OAL from all others. I load 3.0gr of TG @ 1.10". It works on all my CZs/Tanfoglio no problem.

It does gets dirty pretty quick. Are you using reloads? What is your data? I know I can tell the difference in recoil before I shut the valve off to the way it was before. My MPX has more muzzle flip now (running 115gr with 6.9gr of HS-6) than my AR.

I can't move mine because they way it is now. Whenever I get my new one I will try. It should move though. Look on the upper receiver above where the valve should be. Any gas that gets vented, gets vented to that portion of the lower part of the upper rail. Mine was pretty dirty when I had cycling issues.

When I got my MPX, I had issues with it cycle after the first 100 rounds. When I went to clean the piston the cap on the gas valve came off (my didn't have a pin installed). Well the spacers came out and I didn't think much of it and put them back in and installed a pin. Gun still didn't cycle. So I tighten the crap out of it and pinned it pretty much permanently and got it to run. Came to find out there is a specific way the spacers have to go so they act as a spring and bleed off excess gas at X amount of pressure. I believe, I eliminated the possibility of the gun bleeding excess gas and might be able to run some lower PF ammo (haven't gotten a chance to try yet). I did contacted Sig about it and they sent me a replacement anyways so I want to compare the two valves. Here is the link where it tells you how the spacers go. http://www.ar15.com/forums/t_6_45/448281_Sig_MPX_Gas_Valve_Modification.html

I considered one when looking for a PCC but I was concerned with mag changes would take a bit more time that the typical PCC.

Haha I do them too. We throw the flags away weekly.

Haha I do them too. We throw the flags away weekly.

So I finally figured out the whole issue. So when my plug came out the first time, so did the spacers. I though they were just simple spacers. Found the order they are supposed to sit and this puts the cap in the right location to put the pin in the correct spot. With this done, I manage to get the gun to run pretty much anything. Was finally able to run mag after mag to the point I got tired of shooting it (about 350 rounds may be 400). Now I need a red dot since mine went out (Holosun).

So I took the pin I made out and screwed the cap all the way in. Now I can get it to run all the ammo I put through it (didn't try my 147 ammo) and it ran fine as long as I kept the cap tight (kept coming loose). So now to figure out how to keep the cap in place.

So here is the cap. This is what it looked like after the first range trip. Apparently there is is a pin that is supposed to hold it in place. So I installed it and put a pin through it. Took to the range and still doesn't cycle. I think it even got worst. Before it would cycle enough to reset the trigger. Now it doesn't do that.

I'm talking about the cap itself. The one with the 3 holes in front. If you remove it a rod with like 20 tiny spacer comes out.

Did a bit of research and there's supposed to be a pin holding it in place. Mine is missing. So I installed a pin with the cap where it should be. Will see tomorrow how it goes. Not my actual picture but the cap I'm talking about.

Update: Took a look at it now and found the cap on the gas valve loose and easy to rotate with my thumb. Screwed it all the way in but if I'm understanding what I'm reading, there should be a roll pin holding it in place?