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Old September 25, 2011, 09:15 PM   #1
Lawfficer
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Join Date: September 25, 2011
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YHM Supressor killing my accuracy. Why?

Hey everyone, just signed up after lurking because I have a problem that I can't seem to wrap my head around. I have had a Supressor for a while but for various reasons I have not had much time to take it out and really put it through it's paces like I wanted. But recently I have found the time and Im having issues.....

Gun: I have a Accu-Triggered Savage Model 12(Heavy Barrel) in .308 caliber. The barrel was originally 24", but with the Supressor that was just way to long so it was professionally cut down to 20", threaded, and a YHM Phantom QD mount for the suppressor was put on. It was then dropped into a Bell and Carlson stock and the gun is sporting a SuperSniper fixed mil dot 10x scope with single piece rail mount and SuperSniper rings. The Suppressor is a Yankee Hill Machiene(YHM) 7.62 Phantom.

Issue: With the suppressor on, I have no problems with the gun and shooting off a bag rest I can get a 1/2" to 1" group with no problems. They all are grouped nicely like they should be. But When I put the suppressor on, I get a Chaotic pattern of randomness to say the least. It will litteraly scatter the rounds at 100yds. Some rounds are as far up as 5" from the point of impact without the can. And then some are up and off center, but they are almost always raised. (Shooting Federal Fusion 165Gr)

I honestly just don't get it. I was always under the impression that a Supressor does NOT affect the point of impact, but mine does. I have checked the interior as best I can and don't see any baffle strikes.

Ideas, Suggestions, etc???

Last edited by Lawfficer; September 26, 2011 at 12:09 AM.
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Old September 25, 2011, 10:26 PM   #2
rjrivero
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Quote:
Originally Posted by Lawfficer
Issue: With the suppressor on, I have no problems with the gun and shooting off a bag rest I can get a 1/2" to 1" group with no problems. They all are grouped nicely like they should be. But When I put the suppressor on, I get a Chaotic pattern of randomness to say the least. It will litteraly scatter the rounds at 100yds. Some rounds are as far up as 5" from the point of impact without the can. And then some are up and off center, but they are almost always raised. (Shooting Federal Fusion 165Gr)
Presuming you have good accuracy without the suppressor, and erratic patterns WITH the suppressor, I would presume that the threads aren't concentric with the bore resulting in baffle strikes.

Take a look at the suppressor and look for "shiny fins" on the baffles. You may have to look from both the front and the back end. If the baffle strikes are really bad, you may have pieces of the copper jacket left behind/rattling in the can.

You could also remove the bolt, put the suppressor on and look down the bore to see if there are any issues with baffles in the way of the bore.

The other thing that *could* be an issue is the can not being secured tightly and backing off during firing. (Much less likely by the description you provided.)
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Old September 25, 2011, 10:57 PM   #3
Eghad
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+1 for looseness or not being aligned properly with the bore. This is a safety issue as it could result in a catastrophic failure of the silencer which might cause injuries.

It is a possiblity that a silencer could change you POI also. If this were the case you should still get a tight group?

You really need to check this out !
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Old September 25, 2011, 10:59 PM   #4
Lawfficer
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There are no visible baffle strikes that I can see, that was the first thing I checked.

This is with the QD mount, which rachets once its snugged down. I would think that once it's into the racheting, it's secured and wouldnt be jumping teeth when I fire. I would really hate to think the accurancy is dependant on making sure I rachet it down to the same tooth each time.

Last edited by Lawfficer; September 26, 2011 at 12:03 AM.
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Old September 26, 2011, 11:18 AM   #5
NESHOOTER
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The can will change to POI's, a question once the the POI'S change 5'' off target is the grouping in the same spot? I zeroed all my rifles with the can and yes they change poi's when the can is removed.
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Old September 26, 2011, 12:27 PM   #6
Poodleshooter
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If you rule out the following:
1. Baffle strikes
2. suppressor moving on the QD mount
3. QD mount moving on the existing threads

..these are the only ideas I can think of beyond the above:
1. suppressor is acting a muzzle tuner, and this Federal Fusion load is hitting a narrow/bad node, causing variations in the ammo to be exaggerated.
2. The weight of the can may be causing the barrel to bounce off of the stock irregularly during firing. This is only really a problem with a barrel that is only barely free floating, or is in a flimsy stock. I'm assuming you have it in an aluminum bedded Medalist of some sort, not a Carbelite.
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Old September 26, 2011, 02:47 PM   #7
Lawfficer
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Join Date: September 25, 2011
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Well, I may have failed the supidity test. I was bench testing the gun and found that even when into the Racheting, the supressor still has a bit of a wobble to it. It's really hard to notice, but I know little variations at the muzzle will make huge variations down range. When I really crank the supressor down to "Gorilla Tight", the wobble is a lot harder to detect. Im going to make sure that was not the issue once it stops raining. I was pretty sure I had to tight, but I dont know if I went as far as Gorilla tight so more feild testing to come.....

If not, I'm back to square one.
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Old September 26, 2011, 04:31 PM   #8
flight954
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I run a 5.56 stainless YHM Phantom and I don't have any play at all when ratcheted down on the flash hider mount. You may want to call YHM
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Old September 27, 2011, 02:14 AM   #9
Griffin Armament
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If that doesn't stop you problem there is another animal that can surface.

YHM cans use fairly tight blast baffles. If your thread is not concentric, the group dispersion will be negatively effected.

My brother has an Ops 12th model suppressor- he mounted it with a crush washer (as it is designed to do) and we were experiencing 3-4MOA accuracy at 100yds. After a call to Ron at Ops Inc, I inspected it and found that the bore was nearly in contact with the bullet flight path on one side.

I remounted using a machined washer shim and alignment became near perfect. The weapon accuracy became ~1/2MOA.

You want a suppressor bore to be centered on the weapon bore, because the bullet will follow the column of air and will want to center itself in the bore to an extent.

So if your suppressor is pointing right, that is where it will be sending the bullet also. The phenomenon is accompanied by poor accuracy.
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