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Discussion Starter · #1 · (Edited)
Sorry for the wall of text, there is a lot to unpack....

So I just picked up a new MPX born on July 1, 2021. I took it to the range and sighted it in. The first group of three at 25 yards before zero was less than 1”, then after zeroing it I proceeded to get 2 sets of 1” groups supported from my range bag and two sets of maybe 2-2.5” groups unsupported. I was satisfied that I didn’t get a lemon as some people mention on here. Well fast forward a day later at my private range at my house and I re-zeroed in the daylight since my FFL and member range is indoor. It took a bit to re-zero because I made the mistake of adding a bipod to the handguard to help get a perfect zero. Well, this put the zero all over the place and so I took the bipod and magnifier off and re-zeroed and got it back to 1” groups at 25 yards. I set up 13 clay pigeons and knocked them all down standing and moving without missing one. I was impressed. But there was this nagging feeling that the gun is just not accurate after seeing everyone’s posts on here, on Reddit, and ARFCOM.

I really want to use the MPX for self-defense or a backpack gun. I normally use a 10.3” LMT that’s suppressed for bedside and ranch home defense but a nice PCC would do the trick too since I love the folding brace as it makes it so compact to keep in the Wrangler. But can I trust it to be accurate, there have been some weird groups during the zeroing process?

The MPX has been very reliable now with 500 rounds through it with only one stovepipe from some shitty Blazer aluminum I used. I tried all types of ammo, Blazer, Federal, Sig, Winchester, Tula- brass, steel, aluminum. All different types of grains 115, 124, 147, and defensive ammo too. The MPX ate it all like a champ. But there is still this nagging feeling. Can I trust the gun for accuracy?

All of this testing was with the stock birdcage and I’m waiting for my OMEGA 45k to get out of jail (bought for my B&T GHM45.) But I had a talk with an MPX upgrade manufacturer today who said it’s going to be a 60/40 chance my gun won’t like the tri lug and suppressor and my groups will go to hell. I couldn’t possibly use this for SD if that’s the case. Is it worth sticking with the MPX or maybe looking at the APC9K pro or GHM9 with Glock lower? I have an MP5 too but the ergos just aren’t there like they are on the MPX, GHM, or APC9k.

On top of all this, I have a Stribog with upgrades like an aluminum lower that takes scorpion mags and has a Velocity trigger in it. The Stribog shoots amazingly well and always has, and now with a fantastic trigger and reliable mags I think I could literally include it in the conversation but everyone hates on the Stribog (the poor man APC.)

I was warned today that if my barrel is shooting the groups I’m getting to not upgrade to the other option out there that Tim from MAC recommends as I might just not really see an improvement. It seems to be just one of the drawbacks to the design of the MPX is the harmonics of the barrel are affected by muzzle devices and the retention system of the barrel doesn’t help and over-gassing.

So what are people’s thoughts, are there a lot more MPX’s out there that shoot accurately, or am I just seeing the small portion that doesn’t on here, Reddit and ARFCOM or on YouTube like with Tim from MAC? I want to love this gun and I already do but I’m not sure I can trust it when a $1500 Stribog groups so much better than the MPX does. The MPX is okay but it’s not lights out for accuracy.

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Discussion Starter · #2 · (Edited)
Also another question that I brought up in my conversation with someone today that works on MPX upgrades is that putting force in the handguard affects accuracy, like when I put the bipod on the handguard and my accuracy went to hell and I took it off and decent groups retuned. Any ideas why? Would this also mean using your handguard on a barricade would decrease accuracy?
Second question, are there any agencies that use the MPX, and was it ever released why it lost the military PDW contract to B&T with the APC9k Pro with Glock lower?

Last question, there seems to be a very minor amount of play between by handguard and receiver. When I added the Larue index clips it tightened it up, but how could you use a front sight on the handguard rails and expect it to maintain zero? Is there any fix for tightening up the handguard? I saw some people mention bending the index pin between the handguard and receiver that is held in place by the front take down pin.
 

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There are hundreds and hundreds of these being used in USPSA (PCC version) with only barrel length being the difference. If it was not accurate they would not use them. They are shooting thousands and thousands of rounds each year through the MPX. I have one of each. Both are great and shoot very accurately. Never had a feed or ejection issue. As stated above, as a self defense weapon, it only has to be accurate within the normal range of those engagements. Once you get past 50 feet with a self defense issue you are looking at felony jail time time.
 
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Well here's what I'd do if I was you, and may give you some peace of mind too. Since u have a private range.. get yourself the type of universal laser bore sighter that fits inside the tip of your barrel. Then go outside at dusk.. (unless you're lucky and able to find a green laser model that can be seen well during the day.. if so let me know cause mine is red and sucks at day and I need one also lol).. then set it up on a table with a bag. Check to see if it lines up with your sights. It's kinda hard to check a red beam while using a red dot. But it's doable if your patient and flick one off and the other on and vice versa till you're sure they line up. Then try bracing on a barricade as u mentioned.. and so on. Keep testing your theories till you find what's causing your issue. And if it don't change much if any while u do these things chances are it won't wander around as you use it when ya have to either.

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I didn’t read all of your post, it was a very difficult read to get through the wall of text.

I think it’s funny that people complain or call some MPXs lemons… Well, a 4.5” barrel isn’t going to provide allot of accuracy out past 25 yards. My short barrel MPX is a happy 10 yard gun. The 3.5-4.5” barrel is a close combat short distance gun.

The short barrel is MPX is most defiantly a great home defence weapon. Even the “lemons” would be great in the close quarters of any home. The longest shot I can take in my home is 25 yards. If I have someone in my home and I’ve pulled the trigger once, I’m going to pull it at least 10 more times. My personal accuracy during this situation won’t be range perfect by any means. So if my 4” barrel MPX is getting 2-3” at 25 yard.. It’s good enough for me and my home.

Let me also add, allot of the accuracy issues I have read about are when people have installed a suppressor. Not a surprise that issues happen in accuracy. For home defence, I want that crook to hear my gun go BANG.

Also remember, when you read about a person complaining about a weapon it’s because they went seeking help. They wrote about it to try and resolve a problem. So either it’s likely an internet search engine pointed them to a forum that is meta tagging data best. You hardly ever read about happy experiences because they are busy just shooting.
 

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I couldn't get through the whole wall of text either, but you're comparing accuracy from a 4.5" barrel with the Stribog's 8" barrel. That's a significant difference, and I'm not surprised at all to hear that you're finding it easier to be accurate with the Stribog.

A short barrel PCC is a compromise designed for a niche application. With that use-case in mind, I'd say your accuracy at 25 yds is just fine.
 

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If you are being modest and looking for approval and love, you have my vote. If you need to question accuracy then you must be channeling Sgt York.
We used our MPX for HD and SD and as a car gun. Be well
 

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Discussion Starter · #10 · (Edited)
I am sorry for the wall of text. I broke it up more into paragraphs now, but it wasn’t really a situation where I could go “MPX’s rock!” I needed to explain the backstory a bit. There were some weird inconsistencies during the zero process that made me wonder. I understand the use case is different. I should probably find the other target that shows a wandering POI but once it was set the MPX gave me decent groups, but the inconsistency before the zero was troubling.

I know it’s buried in the text but why would a bipod cause issues for the MPX?

Does anyone use these things suppressed?

Does anyone have a solution for the small amount of handguard wobble? The Larue index clip helped but I have seen some people say to slightly bend the pin that indexes with the front take down pin to help tighten it up?

Lastly was there ever a report issued why these didn’t get the military contract versus the AP9k Pro?
 

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Think griffin makes some oversize pins. Like 3 thou oversized. Heard they can fix wobbles. Just a guess tho

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Just sell your MPX and stick with the Stribog or buy a longer barreled MPX.

I have two MPX; a 8” gen 2 and 16” Gen 3. Both are very accurate and I use them both in competition. Ammo will also make a huge difference in accuracy. I reload so my ammo is tailored for my MPX. As for the inconsistency with a bipod, make sure the barrel lug nuts are torque properly. I get the same accuracy with or without a bipod.

You can also put a little o-ring to eliminate the movement or wobble of the hand guard.
 

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I don't have mine yet. But I've seen how the top.. and first few segments of the picatinny rail on the very tip near the muzzle is separate from the receiver picatinny. Mounting a front iron sight on that to bridge that gap may help secure the two together also and eliminate some wiggle too maybe. Place the front post right on that seem perhaps


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The question on the MPX isn't about accuracy unless a suppressor is causing problems. The question is where to get enough parts and ammo to keep an MPX running reliably.

Bill
 

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Discussion Starter · #15 ·
The question on the MPX isn't about accuracy unless a suppressor is causing problems. The question is where to get enough parts and ammo to keep an MPX running reliably.

Bill
Can you explain? Which parts are impossible to get? I just got this and I like to keep a repair kit on hand.
 

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I have a "K" that I SBR'd, and honestly most days I wish I hadn't. I should have sold it in the beginning. It's a neat idea, but not near ready for prime time IMHO. Absolutely the last gun I'd want for self defense.

An ILWT barrel will probably fix any accuracy issues, just don't get it wet and it should run ok.
 

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Discussion Starter · #17 ·
So I went out and checked my zero again today since there was no wind. I torqued my barrel screws to make sure they were in spec and added two small o-rings to the handguard retainer pin to secure it more and I used a padded rest and not a bipod. I would say the MPX doesn't seem to have accuracy issues. I grouped it at 1" or less with Tula steel 115 grain. Last group was off hand standing and running and gunning.
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Discussion Starter · #19 ·
Rob from ILWT is who I talked to on the phone on Sunday. He said my stock barrel was grouping fine and not to upgrade, that says something about Rob that he isn’t in it just for money, he is a good dude. And the stock barrel is fine. He also said don’t use a bipod, the MPX hates it, so I didn’t, and look at the groups.
He will have a tri lug soon that really indexes the taper very soon so I’m waiting, but it’s still 60/40 if my Omega 45k with tri lug will group well. I guess we will have to find out. As far as reliability this little plinker has been flawless except one stovepipe of aluminum garbage blazer out of what maybe 500-600 rounds.
 

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I should mention that I take issue with those saying that there is no justifiable defensive use for guns at longer distances. I can think of many examples, especially in (but not limited to) rural areas. If someone is shooting at me from 100 yards, I'd like the option of returning accurate fire. A more likely scenario is needing to defend someone else at distance. A major reason for a backpack gun is the possibility of an active killer. You might find yourself needing to protect others at a mall, church, park, etc. I like to plan for at least that possibility, however remote. Justifiable shooting can be at close, medium or long range.
 
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