Suppressor opens groups up by 2x - MP-Pistol Forum

Suppressor opens groups up by 2x

This is a discussion on Suppressor opens groups up by 2x within the MP Pistol Tech Help forums, part of the Smith & Wesson MP Forum category; Hi, I have an M&P .40 full size that has a storm lake 4.25" threaded barrel. The gun easily shoots about 2-3" groups off hand ...


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Old September 11th, 2016, 05:35 AM   #1
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Suppressor opens groups up by 2x

Hi,

I have an M&P .40 full size that has a storm lake 4.25" threaded barrel. The gun easily shoots about 2-3" groups off hand at 15 yards without the suppressor, 4" groups at 25 yards if I sandbag it in. Pretty good. It does about the same with the stock barrel or the Storm lake. As soon as I put the suppressor on, which is a Silencerco Osprey .40, the groups open up to about 6-8" at 15 yards. The dispersion of the groups with the can on is both horizontal and vertical. Ammo seems to have no effect, it's the same with 180 gr HST, 165 gr Winchester FMJ, 180 gr Am. Eagle FMJ, etc. I have checked for baffle strikes in the suppressor and am not getting any.

Has anyone else seen accuracy degradation when shooting a suppressed m&p? I'm considering trying a KKM barrel instead of the storm lake to see if there is any difference.

Thanks!
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Old September 11th, 2016, 07:47 AM   #2
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You've shot it again after taking the suppressor off and it goes back to decent accuracy?

I don't know the nomenclature of handgun suppressors, but many of them have a doohickey built into the rear that helps to accelerate the slide to facilitate functioning. I wonder if it's causing the slide to open prematurely? Kinda like what some of us have experienced with stock M&P barrels doing the same thing and getting unacceptable accuracy. If the doohickey can be removed try that. You might get malfunctions without it, but it might narrow down the problem.
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Old September 11th, 2016, 06:28 PM   #3
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Yeah, it has a nielsen device/booster. I don't think I can use it without booster because the booster has the threads that attach to the barrel. Anyway, today I tried cleaning the booster and actually found that it did help a bit! The groups are closer to what they are without the suppressor attached. I'll have to do some more testing with and without the silencer to be sure.
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Old September 12th, 2016, 12:22 AM   #4
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I have fired the 9mm equivalent and any accuracy loss was covered up by my shooting inability.

Was your piston tightened down fully? Any chance you can use the barrel in a different gun or with a different suppressor? The 9mm wouldn't function with a fixed spacer.

Quote:
Originally Posted by BrianK View Post
I wonder if it's causing the slide to open prematurely? Kinda like what some of us have experienced with stock M&P barrels doing the same thing and getting unacceptable accuracy. If the doohickey can be removed try that. You might get malfunctions without it, but it might narrow down the problem.
Hmm... Try an extra power recoil spring??? (Speed Shooter Specialties sells them.)


Suppressor height sights help a lot if you don't already have them.
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Old September 12th, 2016, 06:04 AM   #5
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Harmonics?
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Old September 13th, 2016, 08:50 AM   #6
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Actually I think I pretty much solved it by cleaning the Booster. It was giving me 2-3" groups at 15 yards offhand yesterday. IDK how a dirty booster could affect accuracy, maybe additional weight from all the carbon? Either way it seems to have shrunk groups back to normal.

Yeah, I do have Dawson tall suppressor night sights on it with an adjustable rear.

Last edited by LoneStarWings; September 13th, 2016 at 09:00 AM.
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Old September 14th, 2016, 12:47 PM   #7
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That's good to know. I need to file that one away in the grey matter.

Any idea of how many rounds you put through it since the last time it was clean?
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Old September 14th, 2016, 01:21 PM   #8
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Embarrassingly I'd never cleaned it, probably 250-300 rounds through the can.
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Old September 14th, 2016, 03:50 PM   #9
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I haven't noticed any difference with pistol suppressors, mostly because 1 or 2 MOA doesn't mean much with a combat pistol.

One of our rifle suppressors, the 30 Caliber Yankee Hill for my Savage 270WSM hunting rifle, throws the POI off by about 2 1/4 MOA (5 inches to the upper right at 200 yards). 8 clicks of wind and 6 of elevation took care of it.
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Old September 15th, 2016, 06:16 AM   #10
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Quote:
Originally Posted by LoneStarWings View Post
Embarrassingly I'd never cleaned it, probably 250-300 rounds through the can.
Nothing to be embarrassed about LSW. Now you know, and you educated us.

KRW, that's one of the nice things about Surefire. It might shift POI a hair @ 100 yards, certainly less than 1/2", but the group also shrinks a bit. All totaled, basically no change at all.
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Old September 15th, 2016, 06:24 PM   #11
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Quote:
Originally Posted by BrianK View Post
KRW, that's one of the nice things about Surefire. It might shift POI a hair @ 100 yards, certainly less than 1/2", but the group also shrinks a bit. All totaled, basically no change at all.
That's the only one we have a problem with, it was damaged before I acquired it (slightly bent mount could cause a baffle strike, can't safely shoot 30 Cal. through it). Within 1 MOA for Griffen, AAC, Gemtech, and AMTAC.

Speaking of which: I'm thinking about replacing the AMTAC with the lighter Brevis II for our 13" CQB/HD AR. Any thoughts?
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