MPX with Evo 9 = bad accuracy

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JR1
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MPX with Evo 9 = bad accuracy

Post by JR1 » Fri May 25, 2018 7:29 pm

I have a two-stamp SIG MPX with an AAC Evo-9. Without the can, I get 2" groups at 25 yards with a variety of 147-grain ammo, to include Fed HS, Speer GD, Win ball, and Win JHP.

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When the can is on, I get 5" groups at 25 yards. ...usually with a nice cluster in the middle and 2 or 3 wild fliers. The can is threaded tight on the barrel, but the can still has play where the piston rides in the body of the suppressor. Is that play goofing up my groups? Is there anything I can do to eliminate that play/slop?

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LoboLoco
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Re: MPX with Evo 9 = bad accuracy

Post by LoboLoco » Sun May 27, 2018 10:57 am

Are you using the Fixed Barrel Spacer?
http://www.advanced-armament.com/Improv ... p_720.html

I use a TiRant45 with a fixed barrel spacer installed in place of the standard spring on my MPX, with great results.
The spring is needed for semi-auto pistols to allow them to function. But, on fixed barrels (MPX)- you want it tight - no wiggle.
That's why AAC makes the spacer.

I just ordered the ILWT 4.5 inch barrel with tri-lug, so I'm planning to switch my TiRant piston for the tri-lug adapter.
That will give me quick-connect, and tight.
Be wary of those who seek to govern others. For while they proclaim their moral foundation, and noble intentions, make no mistake - they intend to govern others.

JR1
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Re: MPX with Evo 9 = bad accuracy

Post by JR1 » Sun May 27, 2018 2:50 pm

I am using the fixed barrel spacer. I also am using a new piston for the SIG's oddball left-hand twist. I'm wondering if the counter-threading is part of the issue. I tightened and applied blue locktite to the can's threads, and I rockset the barrel threads. I got a few 2" groups at 25 yards, but then the groups opened up to 5" again. As it turned out the can started to wobble again. The barrel threads were still tight, but the piston rotated inside the can's body.

I can't unscrew the can to inspect it as the locktite set in when it cooled. I'm going to blast some rounds to get it good and hot and take it apart. Hopefully, I can get tight enough to not wobble, but I can't imagine it's possible to tighten it anymore that I did last time.

When I had it on a pistol with the spring in it, you could push in and turn the can to adjust point of impact. There was always a little wobble then too. Is it just the way the can is made, or is there a way to get the piston to stay in place?

Is AAC's new improved fixed barrel spacer meant to fix this problem?

Thanks!

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LoboLoco
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Re: MPX with Evo 9 = bad accuracy

Post by LoboLoco » Mon May 28, 2018 1:05 pm

JR1 wrote:I am using the fixed barrel spacer.

Is AAC's new improved fixed barrel spacer meant to fix this problem?

Thanks!
I was hoping I had the quick fix for you. But, I see you have the spacer.
I've got the improved version. Maybe that's the difference.
Also, mine is .45 cal. So, it has less chance of interfering with the round.
I hope you get it worked out.
Be wary of those who seek to govern others. For while they proclaim their moral foundation, and noble intentions, make no mistake - they intend to govern others.

JR1
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Re: MPX with Evo 9 = bad accuracy

Post by JR1 » Thu Jun 14, 2018 9:51 pm

Any other help for the bad groups I get with the Evo on?

JR1
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Re: MPX with Evo 9 = bad accuracy

Post by JR1 » Sat Dec 01, 2018 4:48 pm

Does anyone make a tri lug adapter for the Evo 9? I can’t find one. I ordered one from Griffin, but it doesn’t fit and AAC doesn’t seem to carry them anymore.

FreetheCans!
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Re: MPX with Evo 9 = bad accuracy

Post by FreetheCans! » Mon Mar 25, 2019 11:48 am

Its not the can here, its the gun, or rather the manufacturer. Sig is using this "taper lock" which doesn't play well with other companies. You need an adapter so that you can use it with other silencers. Get one from Capitol Armory and it should rub some Preparation H on your groups.

https://www.capitolarmory.com/sig-sauer ... ollar.html

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