hhsmiley

Sorry for the long delay in posting to this thread. Life interfered and I did not get to shoot my MPX till last weekend. It appears my issues have been fixed by the use of the +20% recoil springs and use of the o-ring with the extractor. I had no failures in 150+ rounds, and the brass was in a neat pile about 8 ft to my 2 o'clock. Here's a picture of a new extractor spring compared to mine after those 150 + rounds. It appears the spring has taken a very small set. Before, it would have been smashed nearly flat by firing that many rounds. Never in a million years would I have come up with heavier recoil springs to fix an extractor problem, so THANK YOU to everyone for your help. FYI my setup was the o-ring, stock extractor, stock spring, and spring insert. The ILWT extractor is thicker at the back and does not allow the use of the o-ring. I may play around with that extractor later, but for now, it seem like I have something that will work.

I have the 20+ springs and ILWT extractor and hope to get to the range this week to do some testing. Will definitely post the results. Thanks to everyone for the help.

Got it, thanks.

Turns out I've been shooting on the .052 setting. With my 6" barrel shooting 130-140 PF you think 20+ springs and .0625 setting on the gas plug would be my best bet? Right now I'm getting ejection at around 5-6 feet at 2:00.

Pic of my barrel/muzzle device

Update - I had ordered some o-rings and they just showed up. I CAN get the o-ring and spring in using the stock extractor. I guess the next step will be to shoot it that way and see what happens. It bugs me a little that a gun like this may completely rely on a $0.10 piece of rubber to function correctly, but I guess if it works, it works.

I ordered the ILWT extractor today. I may try altering it to allow me to get an o-ring in, but that's only if all else fails. I'd rather mess with a $50 part than an unobtanium part from Sig. What about some kind of positive stop to keep the extractor from squishing the springs? Like a thin metal washer around the spring that will not allow the extractor to compress so far? Seem like it might be a recipe for a broken extractor, but as it is, unless this new extractor magically fixes the problem (and it sounds like it won't) I have a $1,500 gun (paperweight) that will fail within 3 - 4 magazines so really what's the harm?

Yes, I'm using a new insert each time. I'll try shooting it without the muzzle device and see. I suspect I won't be able to get the o-ring to fit either, Maybe with the ILWT extractor...

At one point I sent my upper to Rob @ ILWT to see what the problem was and he was not really able to replicate the problem. He very graciously did that for free and didn't charge me anything for looking at it or for ammo for testing. It's possible they just didn't put enough rounds through it to get the spring to the point of getting smashed and causing problems. At this point I am hesitant to bug him further with this because he's already gone way above and beyond IMO. ILWT is very GTG, both their parts and service. I have tried a Wolff extra power AR extractor spring, standard AR springs, MPX springs from ILWT, and factory Sig MPX springs. All have been smashed. The Wolff had too many coils and I could not get the extractor pin back in with that. I did try cutting off one coil and that spring just got smashed like all the others. Curiously, the Wolff springs would be completely compressed and not allow the pin to go into my AR bolts too, so not sure what's up with that. At this point, I'm going to order the ILWT extractor. I'm afraid I also won't be able to get the extractor pin back in with the BCM kit but I'll go ahead and try that too. Based on the responses, I don't think it's an out of spec bolt or extractor, but maybe there's something to the over gassed thing. The only problem with that is that I have the adjustable gas plug set on the lowest gas setting that will cycle the gun. Any less gas and it doesn't work reliably. I just got done building a 9mm AR with CMMG's "guard" barrel and BCG and am using Endomags. The thing runs like a sewing machine. Wish I'd never bought an MPX, and I would not trust it for a second for "serious" use, but would like to get it to run for 500 rounds or so between replacing springs so I or a buddy could at least shoot a match with it.

I checked the ejector. It's in there good. No movement or anything like that. I'm using the original stock Sig recoil springs. I only have maybe 600-700 rounds through this gun (bought in 2016), so I didn't think they would be anywhere close to needing replacement. I just haven't shot it much because it's been a problem almost from the get go. Most of the time I can pretty well work out a problem and solution to a gun issue but this one has me stumped. I just know I've never been able to get through more than 3-4 mags without the extractor losing tension.

6" barrel Muzzle device is a pretty basic 2 side port brake similar to this pic but without the ports on top. Ammo varies but my handloads are about 1000 fps with 124 gr and the range ammo is 115 gr at around 1200 fps. I'm not sure which setting the plug is on. There are no external markings or way that I can see to determine that. When I installed it, I just rotated it around to different settings until I got the gun to function, and placed a witness mark on the plug and gas block so I'll know where to set it if I ever change it for some reason. When it does extract, my brass is landing in an area about 5-6 ft away slightly forward at about my 2 o'clock. Does that sound normal?

I am definitely getting the spring all the way into the extractor. Seems like the measurements on my bolt/extractor are close to others'. It does look like my spring has taken a bit more of a set though especially after only 100 rounds, and I know from past experience with this gun that if I keep shooting it will only get squished further. This is a gen II and I have shot a mix of handloads and cheap range ammo (Winchester and Blazer Brass). The extraction problems are present for all types of ammo. I've already spent a lot of time and $$$ trying to get this thing to run, so what's another $50? I might as well try that SSI/ILWT extractor. At this point this gun is about 50% ILWT anyway - barrel, gas block and adjustable gas plug. Does anybody use the little donut o-ring in their MPX in addition to the spring/insert?

I don't have the factory parts any more. For numerous reasons in addition to the the ones I've given, sending it back to Sig is not really an option. If somebody has an MPX and could check those measurements, at least then I'll know whether my parts are out of spec and I can go from there. Thanks!

After throwing an embarrassing amount of time and money at the problem of jams with my MPX, I finally determined that I have a problem with extraction. Specifically, my gun seems to wear out/destroy extractor springs extremely fast. After only a few magazines, the spring is much shorter, and extractor tension is greatly reduced. In this picture, on the left is a brand new MPX extractor spring and insert that I ordered directly from Sig. On the right is the same spring after 100 rounds. I understand a spring will take a set, but it lost somewhere between 1/4 to 1/3 of its length. 1. Is that normal? 2. If it's not normal could somebody check a few things on your bolt and extractor? The depth of the hole in the bolt body that the spring fits down into is .168 deep measured from the top of the bolt right behind that machined out area. The depth of the hole that the spring fits into in the extractor itself is .0685. I'm wondering if that might be out of spec and the spring doesn't have as much room as it should and is being crushed? I have tried various springs including standard Sig MPX springs, and various AR springs (standard and extra power). All of them have good tension to start with, but then after a very few rounds the spring is flattened to the point the that the extractor is just "flopping around" almost and doesn't have the strength to pull the case out causing all kinds of problems. I have not tried using a donut o-ring yet, so I may try that, but IMO you should not NEED something like that just for a gun to run normally. BTW sending the gun to Sig is basically not an option. It has an aftermarket barrel and gas block (which I have a feeling they would balk at) and it's an SBR and I don't want to deal with the risk of shipping the thing. The aftermarket barrel and gas block have no relation to the extractor problem, as the gun did the same thing with the factory parts too.

Oh, I forgot to mention (somewhat unrelated). I have an STI .45 magazine and tried it in this gun just for the heck of it. It fits rather snug, and wont drop free, but it locks in and feeds just fine. Could probably get 15-16 rounds in a 140mm mag if anyone wanted to mess with that.

I love this gun but was not really happy with the quality of the adjustable rear sight. Since there are really no options out on the market right now for replacements, I had to get a little...creative. I post this in case anyone is in the same boat and might like to try something similar. I used a welder, drill press, Dremel and files to do this. If you have a mill, that would be easier and the results better. I might replace these with better aftermarket sights some day if they become available, but this seems like it will work OK for now. The front sight is just the sight that came on the gun, cut down to about .16 in height. Stock was around .2 I think. I first shot the gun with the stock height front sight after installing the rear and I was about 5-6" low at about 10-12 yards. If my calculations are right this will bring that up to the right spot. I just drilled a 1/16 hole through the sight for a .60 fiber optic rod and cut a notch for the rod to get some light. The rear sight is this one: http://czcustom.com/shadowh-tacrearsight.aspx The dovetail in the slide is definitely too big for the sight (see crappy MS paint pic), but luckily both are cut at the same angles. There was a tiny gap along the bottom of the sight dovetail and about a .06 gap at the front. It just so happened that I had a sawz-all blade that was this exact thickness so I cut a chunk out of it, welded it to the front of the sight, and dressed it up with files. You can see the little step in front of the set screw. Normally that would not be there. That's the extra piece. I just put a little JB weld on the bottom of the sight to take care of that gap. I squared off where the front of the rear sight blades meet the top of the sight body to give it more of a positive "hook" while I was at it. If anyone would like more pics or has any questions let me know. Thanks for checking this out!

My TS: Finish is silver Gun Kote.

It's Gunkote silver.

Here we go, all pretty again

Gonna be a little ugly till I make it pretty again.

Yeah, if I was going to move the sight more than one time ever, I'd invest in one of those sight pushers. Took the slide to the local range and the gunsmith charged me $10 to remove it.

Well I got the extractor pin out at least . It comes out from top to bottom, driving the pin down from the top. I'm afraid I'm going to ruin the sight or slide beating on the sight so I guess I'll have to take that to an actual gunsmith to have him remove it. I tried dowsing it with penetrating oil to no avail. I even tried an old trick I've used before, and heated the slide up in the oven thinking the metal might expand a little and allow the sight to be removed, but no joy. With a the fairly large set screw holding the sight in place, it doesn't seem necessary to have the sight wedged into the dovetail so tight. Oh well.

Just got my CZ TS and I'm doing a few modifications to it including refinishing the slide, which means I've got to totally strip it down. I can't seem to get the pin that holds the extractor in or the rear sight to budge. Before I whack on it any more with punches and mess something up I thought I better check and see if there's any trick to this. Also, just want to confirm which direction, if it matters, I should be drifting the sight. Thanks.

I only need 4 mags for matches. AFAIK the CZ comes with 3 mags, the Tanfoglio only 1 or 2. So again, that's basically a wash.

Well I ordered a TS from Bud's today for $1,063. Best price I could find. I was trying to decide between the TS and Tanf. Limited. I've owned a Limited before and it was awesome. There were just a few minor things that swayed me to the CZ this time. They are really so similar that things such as cheaper aftermarket magwell, CZ customer service vs. EAA's, and availability made the difference. Planning on doing a few modifications to it so I'll put up some pictures once I get into that.