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Posted: 12/30/2021 11:38:40 PM EDT
[#1]
Welcome, fellow firearms enthusiast
I have not experienced any accuracy issues suppressed vs non-suppressed on an MPX, but I was only trying out an acquaintances |
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Posted: 12/31/2021 1:07:25 AM EDT
[#2]
I have no idea but I feel for ya, I have a banshee that will not feed reliably suppressed and I’ve tried everything, probably going to just sell it for a kp-9, something simple that just works....maybe a larger volume suppressor like a rex mg7/bowers/wolfman would mess with the bullet less
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Posted: 12/31/2021 3:41:53 AM EDT
[#3]
Make sure your bullets are not grazing the endcap of the suppressor.
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Posted: 12/31/2021 6:32:20 AM EDT
[#4]
I have this issue kind of.
My mpx shot like crap with a can. It was also not reliable. Jammed a lot. I even bought ilwt barrel and that didn't help. My mpx is older. Early gen 2. Apparently there were some issues with the shape of the receiver or something back then. Honestly I've just kind of stopped taking it shooting because it pisses me off, kept telling myself I'd send it somewhere to someone to get fixed but never got around to it. So I don't think it's the same problem as what you're having exactly. |
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Posted: 12/31/2021 7:46:46 AM EDT
[#5]
Quote HistoryQuoted: I have this issue kind of. My mpx shot like crap with a can. It was also not reliable. Jammed a lot. I even bought ilwt barrel and that didn't help. My mpx is older. Early gen 2. Apparently there were some issues with the shape of the receiver or something back then. Honestly I've just kind of stopped taking it shooting because it pisses me off, kept telling myself I'd send it somewhere to someone to get fixed but never got around to it. So I don't think it's the same problem as what you're having exactly. I bought the ILWT 3 lug barrel as well as their 4 position gas block and nothing helped. I have heard that if you go with an integrally suppressed MPX that they are quiet but I didn't want to dump any more money into mine. I'm so glad I sold my MPX. |
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Posted: 12/31/2021 7:59:27 AM EDT
[#6]
Quote HistoryQuoted: I have no idea but I feel for ya, I have a banshee that will not feed reliably suppressed and I've tried everything, probably going to just sell it for a kp-9, something simple that just works....maybe a larger volume suppressor like a rex mg7/bowers/wolfman would mess with the bullet less 9mm and .45 ACP run 100% for me suppressed and unsuppressed. .40SW has been very temperamental for me. What caliber are you running? I have a lot of info on my website: https://c3junkie.com/?page_id=164 9mm CMMG RDB, A5 tube, RB5007 hydraulic and Tubb 556 spring. 622 RPM  Same as above but adding a suppressor adds about 60 RPM in the cyclic rate but is still reliable.  I have Gemtech MK9K in that picture but have no issues running a higher back pressure can like the Octane9. I know many have used my recommended buffer tube / buffer and spring combination with great success as well running suppressed. I do know that other spring / buffer combinations have issues when adding a suppressor. I had the same issue when I was trying different combinations for 9mm. I have posted several times that the 9mm and .40SW see a considerable increase in the cyclic rate when suppressed. I also recall that one of my configurations that wouldn't run with a 9mm suppressor worked fine with a .45 ACP suppressor as it was back pressure induced. Now I see no cyclic rate increase in .45 ACP and also have had zero issues getting the .45 RDB to run suppressed or unsuppressed in full auto. (Same buffer / tube and spring combination I use for the 9mm posted above) |
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Posted: 12/31/2021 8:04:17 AM EDT
[#7]
A poor design cannot be fixed. Repeat. A POOR DESIGN CANNOT BE FIXED!
I fell for a SIG716 Patrol rifle that was a POS. Sent it back to SIG and on the third time they replaced the rifle. The second gen rifle was just as bad as the first gen rifle that was sent to them 3 times. Sold it on consignment at a loss with full disclosure. |
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Posted: 12/31/2021 8:49:03 AM EDT
[#8]
Quote HistoryQuoted: I've been running the CMMG Banshee RDB (Radially Delayed Blowback) in full auto suppressed and unsuppressed in 9mm / .40SW and .45 ACP. 9mm and .45 ACP run 100% for me suppressed and unsuppressed. .40SW has been very temperamental for me. What caliber are you running? I have a lot of info on my website: https://c3junkie.com/?page_id=164 9mm CMMG RDB, A5 tube, RB5007 hydraulic and Tubb 556 spring. 622 RPM https://c3junkie.com/wp-content/uploads/2020/04/NoWeightBaseline622RPM-1024x486.jpg Same as above but adding a suppressor adds about 60 RPM in the cyclic rate but is still reliable. https://c3junkie.com/wp-content/uploads/2020/04/NoWeightMK9K-686RPM-1024x471.jpg I have Gemtech MK9K in that picture but have no issues running a higher back pressure can like the Octane9. I know many have used my recommended buffer tube / buffer and spring combination with great success as well running suppressed. I do know that other spring / buffer combinations have issues when adding a suppressor. I had the same issue when I was trying different combinations for 9mm. I have posted several times that the 9mm and .40SW see a considerable increase in the cyclic rate when suppressed. I also recall that one of my configurations that wouldn't run with a 9mm suppressor worked fine with a .45 ACP suppressor as it was back pressure induced. Now I see no cyclic rate increase in .45 ACP and also have had zero issues getting the .45 RDB to run suppressed or unsuppressed in full auto. (Same buffer / tube and spring combination I use for the 9mm posted above) Thanks, you website is great. It’s in 9mm. Been talking to cmmg customer service and they are supposedly sending me “an updated extractor assembly, an o-ring, and a couple of ejector springs to try out.” But I’ll prolly pick up your set-up as well to try out, even tho what I read on your sight about the extractor/headspace just makes me think the design kind of sucks. |
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Posted: 12/31/2021 10:59:42 AM EDT
[#9]
My MPX has been 100% reliable in all shooting, suppressed or unsuppressed. I do not get any gas in the face that others complain about. I do believe that adding the suppressor increases felt recoil.
My next step is probably going to be trying a thread adapter. Like I mentioned in the OP, ILWT makes an adapter Navy Style MPX 3-lug adapter this adapter is supposed to mate perfectly with the MPX barrel taper and provide a 3-lug and also 1/2"-28 thread. I have a friend with an Obsidian 9 and an Obsidian 45. He also has a 3-lug mount for the 9. If that doesn't work I don't know what I will do. I really, really like this gun but this is ridiculous. Chris_M |
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Posted: 12/31/2021 11:46:54 AM EDT
[#10]
If you have access to a .45 can I’d be interested to see how it does. As previously mentioned your bullets may be clipping the end cap. With a larger aperture the groups may shrink.
Just an idea. |
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Posted: 12/31/2021 1:08:58 PM EDT
[#11]
Quote HistoryQuoted: If you have access to a .45 can I’d be interested to see how it does. As previously mentioned your bullets may be clipping the end cap. With a larger aperture the groups may shrink. Just an idea. I just looked at the end cap under lighted magnification. I do not see any evidence of a bullet clipping the end cap. I still intend on trying the Obsidian 45 as soon as I get an adapter to make it work. |
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Posted: 12/31/2021 4:09:32 PM EDT
[#12]
Chris,
I had a Gen 2 mpx-k model that had the same issues. Shot fine without a suppressor. Throw on a TiRant 9 with the LH piston and it opened up my groups to ~8-10” at 50 yds. A taper adapter did nothing to fix the issue. The odd part was that it may put 4 rounds within 3” of each other, but the next 3 would be 6” to either side of the center group. I also have an SRD9 with the direct thread mount for an MPX and it was no better. I ran gold dot, HST, golden saber, critical defense, and everything else i had through it with the same results. Sent it back to Sig with a full write up and they tell me it shoots 1.5” at 50yds for them with no issues. Sold it to a buddy who runs it with an old AAC Evo9 and loves it. He’s fine with it being a <25yd gun with mediocre accuracy since I gave him a fair deal. Sell it and get an MP5 or B&T offering. |
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Posted: 12/31/2021 4:52:40 PM EDT
[#13]
Quote HistoryQuoted: Thanks, you website is great. It's in 9mm. Been talking to cmmg customer service and they are supposedly sending me "an updated extractor assembly, an o-ring, and a couple of ejector springs to try out." But I'll prolly pick up your set-up as well to try out, even tho what I read on your sight about the extractor/headspace just makes me think the design kind of sucks. |
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Posted: 12/31/2021 5:25:08 PM EDT
[#14]
Quote HistoryQuoted: I've been running the CMMG Banshee RDB (Radially Delayed Blowback) in full auto suppressed and unsuppressed in 9mm / .40SW and .45 ACP. 9mm and .45 ACP run 100% for me suppressed and unsuppressed. .40SW has been very temperamental for me. What caliber are you running? I have a lot of info on my website: https://c3junkie.com/?page_id=164 9mm CMMG RDB, A5 tube, RB5007 hydraulic and Tubb 556 spring. 622 RPM https://c3junkie.com/wp-content/uploads/2020/04/NoWeightBaseline622RPM-1024x486.jpg Same as above but adding a suppressor adds about 60 RPM in the cyclic rate but is still reliable. https://c3junkie.com/wp-content/uploads/2020/04/NoWeightMK9K-686RPM-1024x471.jpg I have Gemtech MK9K in that picture but have no issues running a higher back pressure can like the Octane9. I know many have used my recommended buffer tube / buffer and spring combination with great success as well running suppressed. I do know that other spring / buffer combinations have issues when adding a suppressor. I had the same issue when I was trying different combinations for 9mm. I have posted several times that the 9mm and .40SW see a considerable increase in the cyclic rate when suppressed. I also recall that one of my configurations that wouldn't run with a 9mm suppressor worked fine with a .45 ACP suppressor as it was back pressure induced. Now I see no cyclic rate increase in .45 ACP and also have had zero issues getting the .45 RDB to run suppressed or unsuppressed in full auto. (Same buffer / tube and spring combination I use for the 9mm posted above) |
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Posted: 12/31/2021 9:36:52 PM EDT
[#15]
Quote HistoryQuoted: It definitely has it's shortfall's but IMHO, it is the best 9mm AR variant on the market right now due to it's delayed blowback (great for suppressors), easy to work on and tuneability. I would take it over any other 9mm even if I had to change ejector springs every 1K which BTW, there are some guys at the match I go to that are over 3K with no issues and they are shooting suppressed to. Which goes back to my thinking they have some barrels that have inconsistent head spacing. Ok...well you have a lot more experience than me so that means a lot...do you happen to know if I put the longer tube on the gun will it still be a “pistol” or do I need to sbr it if I do that? |
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Posted: 12/31/2021 9:58:24 PM EDT
[#16]
Quote HistoryQuoted: do you happen to know if I put the longer tube on the gun will it still be a "pistol" or do I need to sbr it if I do that? |
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Posted: 12/31/2021 10:19:43 PM EDT
[#17]
Sadly the MPX barrel is garbage. If you even look at it wrong it will throw basketball sized groups. If you put anything, and I mean anything on it, you’ve got a 12 MOA barrel. It sucks, but you need to buy an ILWT barrel if you get an MPX.
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Posted: 1/1/2022 9:07:13 AM EDT
[#18]
I had always shot my MPX with 150 grain Syntech, and typically got about 3” groups at 25 yards. I pretty much just wrote that off to my astigmatism when using the red dot, and decided it was acceptable. Its the newest generation MPX K with the 4.5” barrel. I run a Wolfman with ILWT 3-lug muzzle device.
This topic has come up a few times lately though, so I decided to do a little more rigorous evaluation. Subs shot acceptably well again. 115 grain supers all over the place. 6” groups at 25 yd. I get my buddy (who just got eye surgery a month ago and now has perfect vision and no more astigmatism) to shoot a few five-round groups to compare. Same shit. I tried with my Nitro N2O and my Omega 9k, and the results were the same. So I back-ordered the ILWT barrel. Gonna try with 3-lug first, I think, but I may just end up going keymicro, theoretically to decrease variability. Anyone know the lead time on these back orders? I didn’t see it anywhere on their site, but i admittedly didn’t look very hard. |
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Posted: 1/1/2022 9:14:20 AM EDT
[#19]
You're not the only one, this has been an issue brought up by others before
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Posted: 1/1/2022 9:17:07 AM EDT
[#20]
We had this issue with several guns at work. We have 4 1/2” barrels and Rugged suppressors. The guns shoot “ok” unsuppressed, but they are very inaccurate with the can attached. We also had a few baffle strikes. Baffle strikes would explain the accuracy, but we still haven’t resolved why we are getting them.
On a side note, we got ahold of an 8” barrel and tested it and the accuracy was much improved. I’m interested to see other people having similar issues. Threads are better with pictures. This is a bullet drop test with 147 grain G2 from the short barrel.  Attached File |
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Posted: 1/10/2022 1:18:03 PM EDT
[#21]
I had a similar and wicked problem with my mpx-k (Newest Gen).
I was getting 5" groups at 25 FEET with my rugged obsidian 9 on a tri-lug. I then tried it with just the tri-lug, with their muzzle device, and with no muzzle device. I tried 115gr, 124gr, 147gr and 158gr with all the same results. I couldn't hit a 12" steel plate at 50m. I sent the firearm back to Sig twice. The first time they 'fixed' it and sent it back, and I had the exact same issue. The second time, they told me it shot fine with 147gr speer ammo, and since it would shoot with a commercially available load, there was nothing wrong. I sold it soon afterwards with the disclosure that it sucked and replaced it with the (uglier but much more accurate and consistent) B&T APC9 Pro Glock |
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Posted: 1/10/2022 4:30:04 PM EDT
[#22]
Well. I sure wish that I knew that was how Sig would handle it. I just sent mine in after lengthy discussions of the problem. They are the ones that encouraged me to send it in, instead of just dismissing it. So it got my hopes up. I sure hope they can fix it.
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Posted: 1/27/2022 6:44:59 PM EDT
[#23]
You can add me to the list of people who are disappointed with their MPX's accuracy. My K shoots around 8" groups at 25 yards with anything except the factory birdcage on the muzzle of the factory barrel. I broke down and bought an ILWT 4.5" barrel. That brought the groups down to usually 4" or less.
Mine never gets any range time anymore, and honestly, if I hadn't of SBR'd it, I'd have sold it a long time ago. |
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Posted: 1/27/2022 7:43:12 PM EDT
[#24]
Dang. This is not encouraging. I love the MPX K. I installed the ILWT Navy 3 lug adapter and just e-filed a Wolfman.
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Posted: 1/27/2022 10:30:18 PM EDT
[#25]
Well, I have an update. I ended up sending my MPX back to SIG. They checked it out and said it was all good and everything was in spec. They put their SRD9 on it and fired for accuracy. It produced a 2" and a 3" five shot group @ 25yds, they included the targets when they returned it. Their view is that if it shoots good without a can and shoots good with their can, then it is not the gun.
They took the position that there must be something wrong with my silencer. I told them that I have no problems with any of the other guns that I have shot it on. I attempted to explain to them that a quick Google search will turn up dozens of examples of my exact issue. The reply was that it must be a compatibility issue and not their fault, some guns just don't work with certain accessories. The rep said I could buy a SIG silencer and that there would be no issues. They offered to sell me a barrel, with no guarantees it would fix the issue. There was nothing else that they could do. Needless to say, when I got it back and shot it, there was no change at all. Four different types of ammo and a handload of my own all produced the same terrible accuracy while suppressed. No can and it is awesome, but I bought it to shoot full time suppressed. I think that all of this is total garbage. |
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Posted: 1/28/2022 7:18:46 AM EDT
[#26]
Does a fixed mount (no piston) still have these issues? I’m asking as it seems like the suppressed only accuracy issues exist with the tapered barrel combined with incompatible attachments, 3 lugs, and boosters, with the latter two having axial play.
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Posted: 1/28/2022 2:14:34 PM EDT
[#27]
Quote HistoryQuoted: Does a fixed mount (no piston) still have these issues? I’m asking as it seems like the suppressed only accuracy issues exist with the tapered barrel combined with incompatible attachments, 3 lugs, and boosters, with the latter two having axial play. The only option I have available to me is to use with my TiRant 9 is a M13.5x1LH piston and a fixed barrel spacer. I use this with and without the Sig taper adapter and get the same results. I am not aware of a fixed mount specifically for the MPX with the tapered shoulder that works with the TiRant. My issue with all of this is that there are many people running silencer on various platforms and configurations and do not exhibit these same issues. There are obviously problems here and there with something not being concentric or whatever. But I have never seen an issue so widespread through a product line such as this. |
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Posted: 1/28/2022 3:50:52 PM EDT
[#28]
As an option, you could get a SiCo adapter from ECCO (I use one on my TiRant 9s) and use a Rugged direct thread that indexes on the muzzle.
I suspect if it shoots well unsuppressed, but poorly suppressed, it's probably the taper, muzzle device, or mount, and hopefully less likely the threads, muzzle, or suppressor. Waiting on a stock and trigger for mine, but I'll be using a Rugged direct thread Omega 9k and will find out for myself. |
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Posted: 1/28/2022 4:14:40 PM EDT
[#29]
Quote HistoryQuoted: The only option I have available to me is to use with my TiRant 9 is a M13.5x1LH piston and a fixed barrel spacer. I use this with and without the Sig taper adapter and get the same results. I am not aware of a fixed mount specifically for the MPX with the tapered shoulder that works with the TiRant. My issue with all of this is that there are many people running silencer on various platforms and configurations and do not exhibit these same issues. There are obviously problems here and there with something not being concentric or whatever. But I have never seen an issue so widespread through a product line such as this. My only 9mm suppressor is a CGS Kraken. I've tried it direct thread with a fixed barrel spacer, and using their Trip-lug. I've tried three different trips-lug adaptors on the barrel, One from HK parts, one from Griffin, and one from ILWT. All three were essentially the same results. I did a bunch of reading after my first suppressed range trip. This issue only seems to happen with the 4.5" guns. One theory was the guns are over gassed, so the bolt carrier would normally be reaching full recoil right after the bullet leaves the muzzle. When you add some non-rifled length to the barrel, the movement of the recoiling parts imparts moment to extra length on the muzzle, and then disrupts the flight path of the bullet. Sounds plausible, at least. I have some ILWT restricted gad plugs I was meaning to try out and see if that made any difference. If SIG would ever get the 8" barrels back in stock, I'd probably use buy one of those, and be done with this mess. |
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Posted: 1/28/2022 4:58:41 PM EDT
[#30]
Quote HistoryQuoted: Well, I have an update. I ended up sending my MPX back to SIG. They checked it out and said it was all good and everything was in spec. They put their SRD9 on it and fired for accuracy. It produced a 2" and a 3" five shot group @ 25yds, they included the targets when they returned it. Their view is that if it shoots good without a can and shoots good with their can, then it is not the gun. They took the position that there must be something wrong with my silencer. I told them that I have no problems with any of the other guns that I have shot it on. I attempted to explain to them that a quick Google search will turn up dozens of examples of my exact issue. The reply was that it must be a compatibility issue and not their fault, some guns just don't work with certain accessories. The rep said I could buy a SIG silencer and that there would be no issues. They offered to sell me a barrel, with no guarantees it would fix the issue. There was nothing else that they could do. Needless to say, when I got it back and shot it, there was no change at all. Four different types of ammo and a handload of my own all produced the same terrible accuracy while suppressed. No can and it is awesome, but I bought it to shoot full time suppressed. I think that all of this is total bullshit. Stock configuration it shoots fine. As tested by them, with one of their direct thread suppressors, it shoots fine. You test w/ your adapter and can and it does not. What are they supposed to do? Maybe they should state 'only run w/ LH direct thread suppressors' or something like that. Sucks that it doesn't like your configuration. |
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Posted: 1/28/2022 7:56:49 PM EDT
[#31]
Well for starters, I would like for them to acknowledge that there is a compatibility issue with the MPX K and nearly every 9mm silencer on the market, instead of acting like it is the fault of me or my can, or pretending like the problem doesn't exist. I guess if they did, they would be obligated to fix it. A quick Google search will turn up dozens of cases where people have problems with the MPX K and silencers of all makes and models. There are even cases where merely exchanging the bird cage flash hider for another muzzle device (not a silencer) such as a brake, mount, or even just a piston, can cause all of these same issues.
I find it hard to believe that their can functions flawlessly and everybody else has problems even changing out the flash hider. Did I mention that neither the Sig SRD9 or the MODX-9 have a piston designed to be compatible with the tapered barrel of the MPX? Nope, they are made to work with a typical pistol barrel. Sig will tell you that their can seats on the shoulder of the barrel before it ever engages the taper. Well I measured that part on my barrel. The OD of the threads are 0.5275 and the OD of the shoulder they are referring to measures 0.531, that is a difference of 0.0035. So are we to believe that their can seats on a shoulder that is literally the same as the thickness of a piece of notebook paper? Also, how is it that a company such as Sig, can design a firearm such as the MPX and not design it to be compatible with any silencer on the market. Especially in current times where so many people are shooting suppressed. |
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Posted: 1/28/2022 7:59:04 PM EDT
[#32]
If you have a factory Sig MPX K with the 4.5" barrel and are shooting it suppressed, please tell me what your suppressor is and what type of accuracy you are getting.
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Posted: 1/28/2022 10:00:24 PM EDT
[#33]
I’ve got a current production MPX K but my suppressor is still in jail…8 months yesterday so it could be any day now.
It’ll be a DA Wolfman. I am planning to run it DT with a 13.5 LH adapter I already have. You’re right, you are far from the only person having this issue…it’s common enough to be found on the web easily. It actually seems common enough I am considering selling mine and getting a B&T before my stamp finally comes in because I’m concerned about causing a baffle strike with my brand new can. I’m really not even all that happy with the accuracy with the factory FH to be honest. It’s usable I guess but really not very impressive. I’ll let you know what I see when my can finally clears… |
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Posted: 1/28/2022 10:57:47 PM EDT
[#34]
Quote HistoryQuoted: Well for starters, I would like for them to acknowledge that there is a compatibility issue with the MPX K and nearly every 9mm silencer on the market, instead of acting like it is the fault of me or my can, or pretending like the problem doesn't exist. I guess if they did, they would be obligated to fix it. A quick Google search will turn up dozens of cases where people have problems with the MPX K and silencers of all makes and models. There are even cases where merely exchanging the bird cage flash hider for another muzzle device (not a silencer) such as a brake, mount, or even just a piston, can cause all of these same issues. I find it hard to believe that their can functions flawlessly and everybody else has problems even changing out the flash hider. Did I mention that neither the Sig SRD9 or the MODX-9 have a piston designed to be compatible with the tapered barrel of the MPX? Nope, they are made to work with a typical pistol barrel. Sig will tell you that their can seats on the shoulder of the barrel before it ever engages the taper. Well I measured that part on my barrel. The OD of the threads are 0.5275 and the OD of the shoulder they are referring to measures 0.531, that is a difference of 0.0035. So are we to believe that their can seats on a shoulder that is literally the same as the thickness of a piece of notebook paper? Also, how is it that a company such as Sig, can design a firearm such as the MPX and not design it to be compatible with any silencer on the market. Especially in current times where so many people are shooting suppressed. I'd bet they tested it either with the SRD9-MPX or the MIL-SRD9-MPX, made specifically for the MPX. Good question on the MODX-9, it does ship w/ the 1/2x28 piston, a fixed spacer, extra spring, and the M13x1LH piston. They should definitely have a native MPX option w/ the new gen cans and that's something I'd want an answer on. FWIW: a MIL-SRD9-MPX lives on my 4.5" MPX. |
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Posted: 1/28/2022 11:42:31 PM EDT
[#35]
Quote HistoryQuoted: I'd bet they tested it either with the SRD9-MPX or the MIL-SRD9-MPX, made specifically for the MPX. Good question on the MODX-9, it does ship w/ the 1/2x28 piston, a fixed spacer, extra spring, and the M13x1LH piston. They should definitely have a native MPX option w/ the new gen cans and that's something I'd want an answer on. FWIW: a MIL-SRD9-MPX lives on my 4.5" MPX. SilasB, It sounds like you have been holding out on us. We need more details on your setup. Sig did not mention anything about a special suppressor for the MPX. It looks like the version you are referring to is made of different materials (Inconel) to hold up to sustained full auto firing schedules. In fact I asked if the piston/mount had a taper on it to match the taper on the MPX barrel. The answer was no, the rep said it was just a standard piston and that the MPX does not require anything other than a M13.5x1LH thread. Remember they said it seats on the shoulder directly behind the threads, the one that is 0.0035", not the taper. Maybe you could post a pic of the back of your piston so that we can see what the back of it looks like. I would also like to see a pic of exactly how far it threads onto the barrel in relation to the tapered portion. It possibly could be seating on the muzzle/crown of the barrel. |
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Posted: 1/28/2022 11:59:00 PM EDT
[#36]
After a little more digging, it appears that the MIL-SRD9-MPX was a can that was offered in a very limited edition small batch run. It appears to have a fixed direct thread mount in the back and not a piston for use on tilt barrel semi-auto pistols. I could see this making a definite difference, especially if the back of the can is machined in a way to receive the taper of the MPX barrel.
However, Sig rep said they used a regular SRD9 with a piston for testing on my gun. |
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Posted: 1/29/2022 1:15:58 AM EDT
[#37]
I have an early Gen2 with the exact same issue. I also have a Tirant 9 suppressor. I even bought the ILWT 4.5” barrel and it did not make any difference. I tried the adjustable gas block and heavier recoil springs. I ended up selling the ILWT barrel in EE with only a couple hundred rounds on it. Accuracy is just fine with the factory birdcage. It shoots even better with a 8” barrel.
Rob recommended me to remove gas block completely and fire a few test rounds which would make it single shot to see if there was any improvement. That should show if it is a gas or blowback issue or if the muzzle device itself. It is very likely the Tirant 9 has more back pressure than other suppressors exacerbating the issue. The over gassing could be causing the bolt to release early preventing the bullet from stabilizing properly. It is extremely frustrating, but I can’t bring myself to sell the gun after all I have invested. |
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Posted: 1/29/2022 1:19:22 AM EDT
[#38]
Correct, the -MPX cans were direct thread boosterless and had a matching taper. They were in production for 5+ years, but never sold in great volume.
I'll mount a MODX-9 tomorrow and see what the fit is like while grabbing some pictures. |
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Posted: 1/29/2022 1:30:50 AM EDT
[#39]
Yeah I don't know what this means, but I got a ilwt 4.5" barrel and with an omega 9k on the machined in 3lug I noticed I couldn't hit a 10" steel plate at 60 yards or so.
I never did any actual accuracy testing but I also have the issue of constant jamming. So I just kind of leave my sbr'd mpx in the safe. It just frustrates me whenever I take it out. |
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Posted: 1/29/2022 8:34:15 AM EDT
[#40]
Quote HistoryQuoted:...the rep said it was just a standard piston and that the MPX does not require anything other than a M13.5x1LH thread. Remember they said it seats on the shoulder directly behind the threads... They were mistaken, it seats on the muzzle, just like metric pistol barrels. That’s why I was suggesting you eliminate the booster, get an adapter, and direct thread. Doing so will remove lots of variables. |
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Posted: 1/29/2022 8:50:31 AM EDT
[#41]
It's really unfortunate that this still seems to be widespread. I really like the size, features, ergo's, etc. of the MPX, but if I bought one, it would live its life with a can on it. Not willing to gamble $2k-ish on the gun, plus a stock and a stamp, and then potentially have to pour more money into it to (maybe) get it to shoot decently suppressed. Hopefully they get it fixed.
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Posted: 1/29/2022 10:25:35 AM EDT
[#42]
Quote HistoryQuoted: They were mistaken, it seats on the muzzle, just like metric pistol barrels. That’s why I was suggesting you eliminate the booster, get an adapter, and direct thread. Doing so will remove lots of variables. I would love to, but I am not aware of a direct thread option for a TiRant 9. I would even consider having one custom made, but Sig will not give up the technical drawings for the muzzle threads and attachment method. Not to mention they don't seem to know where the muzzle device is supposed to seat, and I have been talking to their "Team Lead". How can they not know? The flash hider seats on the taper. There is no way I would want something to seat on the muzzle/crown portion of the barrel. In my opinion anything that touches the crown area has the potential to distort it, and since that is the last part of the barrel that the bullet touches, anything that distorts it has potential for accuracy issues. Yes, I know that has been done, but still needlessly asking for trouble. I would even consider buying another can, I have been wanting another one anyway, but I sure don't want to pay the money, go through the wait, and be in the same situation all over again. Bottom line is it should not be this difficult, and I don't think Sig cares. |
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Posted: 1/29/2022 10:37:48 AM EDT
[#43]
Quote HistoryQuoted: Bottom line is it should not be this difficult, and I don't think Sig cares. They don't. Sig doesn't get my money for this type of shit. |
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Posted: 1/29/2022 10:57:22 AM EDT
[#44]
Sig's level of 'care' about other people's products is probably pretty low. They want to sell Sig accessories for Sig products. Now, the idea that they could sell more Sig products if they played nicely with others has a lot of merit.
If you have the booster/Nielsen spring still on, as the other poster stated, that's not helping. That energy, at the right time, helps the browning action complete the cycle of operation. On a fixed barrel, that energy is now doing what? At the end of your barrel. First picture showing how the MIL-SRD9-MPX (and SRD9-MPX) seat on the MPX. Second picture shows the MODX-9. Third shows the matching taper on the MIL-SRD9-MPX   
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Posted: 1/29/2022 11:03:22 AM EDT
[#45]
Great pics, thank you very much. So the big question, how does it shoot with both?
As for the spring in the Nielsen device, I do not use it with the MPX. I have the 13.5x1LH piston and I use a fixed barrel spacer. I have tried it with and without the Sig taper cap. |
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Posted: 1/29/2022 11:22:02 AM EDT
[#46]
my mpx gen 1 with tirant did the same thing acc did nothing and repainted it?? sent it to ecco had them recore it and put standard adapter on it then you can get any ones tri lug mount and tri lug adapter , i used sico. now its fine same groups suppressed and un suppressed no shift in point of aim. I understand they may be able to sell you tirant to standard adapter with out sending it in?
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Posted: 1/29/2022 11:29:52 AM EDT
[#47]
The MIL-SRD9-MPX lives on the MPX and it shoots lights-out. I do want to try the MODX-9 in different lengths, but first I want to find out if there's going to be a specific MPX end piece or piston. Note in my picture of the MODX-9 I did not have the piston seated correctly on the can body, but it is tight to the barrel threads w/ out the shoulder piece.
MODX w/ the pistons. Second picture is my MPX normal configuration.  
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Posted: 1/29/2022 11:35:20 AM EDT
[#48]
Quote HistoryQuoted: my mpx gen 1 with tirant did the same thing acc did nothing and repainted it?? sent it to ecco had them recore it and put standard adapter on it then you can get any ones tri lug mount and tri lug adapter , i used sico. now its fine same groups suppressed and un suppressed no shift in point of aim. I understand they may be able to sell you tirant to standard adapter with out sending it in? Ok, so did changing the baffles fix it or was it the changing of the mount? Was the re-core done with K baffles like the originals, or are they clipped cones or radials? So you have an adapter to adapt TiRant threads to a standard mount thread, then a tri-lug in that adapter on the back of the can. Then you have a tri-lug adapter on the MPX barrel? And final question, is it a 4.5" barrel? Thank you all for all the input. It is really appreciated |
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Posted: 1/29/2022 12:38:29 PM EDT
[#49]
Quote HistoryQuoted:I would love to, but I am not aware of a direct thread option for a TiRant 9. Quote HistoryQuoted:I would love to, but I am not aware of a direct thread option for a TiRant 9. I already explained how in post 28, scroll up. Quoted:There is no way I would want something to seat on the muzzle/crown portion of the barrel. In my opinion anything that touches the crown area has the potential to distort it, and since that is the last part of the barrel that the bullet touches, anything that distorts it has potential for accuracy issues. This makes no sense. What do you think your piston seats on?!? The muzzle. |
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Posted: 1/29/2022 1:06:34 PM EDT
[#50]
Quote HistoryQuoted: This makes no sense. What do you think your piston seats on?!? The muzzle. Well, I did explain my concerns with anything seating on the muzzle/crown portion of the barrel and how this could potentially distort the crown causing accuracy issues. If something seats directly on the muzzle, then that object is torqued down against the crown of the barrel, distortion is likely to occur. The crown is the last thing the bullet touches when exiting the barrel. The factory MPX flash hider seats on the taper of the barrel, not the crown portion of the barrel. Barrels threaded 1/2"-28 have a 90 degree shoulder directly behind the threads for a muzzle device to seat on. This type of connection does not touch the crown of the barrel. Also, Sig gave me a 90 degree taper adapter to use to give a square shoulder so that the piston would seat on it instead of the muzzle or taper directly. This "taper cap" as they call it, did not change anything in regards to accuracy. |
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