looking for 9MM AR vs Sig MPX observations

[stormblue]

Anyone shoot both a 9MM AR and Sig MPX? What are your observations on the MPX vs AR?

[jared91]

I have built a 9mm AR with a QC10 lower and 4" barrel. I can't get it to run right. Its blow back operated. I own a Gen 2 mpx. I absolutely love it. It is piston driven, and has eaten all the ammo I have thrown at it, from monarch 115gr steel case, to AE147gr subs. All suppressed. I am very very pleased with the MPX.

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[KITTEN_FRENZY]

I have built a 9mm AR with a QC10 lower and 4" barrel. I can't get it to run right. Its blow back operated. I own a Gen 2 mpx. I absolutely love it. It is piston driven, and has eaten all the ammo I have thrown at it, from monarch 115gr steel case, to AE147gr subs. All suppressed. I am very very pleased with the MPX.

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What malfunctions do you have? Glock or Colt mags?
And what's your setup?

[jared91]

What malfunctions do you have? Glock or Colt mags?
And what's your setup?

Glock mags.
Double and triple feeding 115gr, with a slash heavy buffer and spring. Will not cycle 147gr subs at all.

Same as above with a JP 9mm SCS buffer system.

QC10 4" barrel, JP 9mm bolt, Geissele SSA-E trigger, and a Vltor upper.

I am completely stumped on this thing.

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[KITTEN_FRENZY]

Glock mags.
Double and triple feeding 115gr, with a slash heavy buffer and spring. Will not cycle 147gr subs at all.

Same as above with a JP 9mm SCS buffer system.

QC10 4" barrel, JP 9mm bolt, Geissele SSA-E trigger, and a Vltor upper.

I am completely stumped on this thing.

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It seems like there are a lot more issues with Glock lowers than Colt.
No issues with the SSA-E? That's one that QC10 has on their compatibility page that has known issues.

[jared91]

It seems like there are a lot more issues with Glock lowers than Colt.
No issues with the SSA-E? That's one that QC10 has on their compatibility page that has known issues.

Well shit. I'll have to throw a stock trigger in there and see what happens

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[KITTEN_FRENZY]

Well shit. I'll have to throw a stock trigger in there and see what happens

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Doubt it'll fix the double/triple feeding, but it's worth a shot hah
147gr subs? Aren't most 147s subsonic out of a 4" barrel anyway?

[jared91]

Doubt it'll fix the double/triple feeding, but it's worth a shot hah
147gr subs? Aren't most 147s subsonic out of a 4" barrel anyway?

I think I made it a double negative. I think all 147s are subsonic.

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[themonk]

I shot an MPX a bit and didn't think it was worth it. I also would much rather have an SBR 556 or 300 blk for social work. So I only see the MPX as a toy. The MPX did get me to build a 9mm upper on the cheap and it is a great toy and super quiet. My logic was you could build an upper for $500-$600 and get close to the same toy.

Now, if I was going to use it for something other than an range toy I would buy the MPX. It's a great gun and enjoy it more than an MP5.

[stormblue]

I want a 9mm rifle, with controls similar to an AR15, to shoot steel. I keep on going back and forth between a MPX and a Colt pattern 9mm AR. I'm a little concerned about function issues with a roll your own 9mm AR. The main down side to the MPX, for me, is that it's made by Sig. I still have a bad taste in my mouth from a SIG556.