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Old September 25, 2011, 09:15 PM   #1
Lawfficer
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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
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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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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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Old January 15, 2023, 09:42 AM   #10
Wyldeshot
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OP. Did you ever figure this out?

I pretty much have the exact situation. I have a 12fv Savage. Went from 26” to 20” and put in a Bell and Carlson stock. Accurate is all over the place with the suppressor on. Going back to the range this week to shoot without the suppressor.
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Old January 15, 2023, 03:10 PM   #11
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Shortening a barrel, and hanging anything off it can change the harmonics, and that can change both group size and point of impact.

There may be nothing wrong with your "can" but the fact that it is there, changes how the barrel vibrates on firing. Additionally, any thing hung on the barrel that isn't "tight" can vibrate the assembly differently with every shot.

Clip a bayonet onto your battle rifle and see what the difference is. Folded vs unfolded bayonet on the SKS, bipod that clamps on the barrel, suppressor, muzzle brake, and many other things, all can possibly create changes in your POI and group size. And, especially if they are LOOSE.

Anyone who told you a suppressor does not affect the point of impact was either lying, or did not understand. Putting a can on a 9mm MP5 and shooting silhouettes at 25M might not be a noticeable change. Doing that with a .308 bolt gun shooting at 100m+ is a much different thing.

You're saying your suppressor "wobbles" when it should be tight. That's NOT a good thing. Not only is it going to shoot your POI and accuracy in the butt (random alignment possibly changing shot to shot rarely produces good accuracy, but it indicates that your barrel and supporessor are not properly fitted to each other.

When you had the barrel work done, did you have the suppressor you are using? Did you give it to the smith and say "fit this to my barrel??" or did you have them shorten, recrown and thread the barrel, THEN bought your can and assumed it would be a perfect fit??

Everything in the firearms world is not "plug and play" and even when they are supposed to be, sometimes, they aren't.

I'd say your random patterns with the suppressor attached is due to it not being properly fit to your barrel. If you can feel movement its WAAY too loose!!

Get that fixed, first. Then see what happens. Odds are you will have a different point of impact with the can on and the can off, but they should be consistent. Loose isn't consistent for anything but "loose".

Good Luck!
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Old January 17, 2023, 12:02 PM   #12
Brian Pfleuger
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Quote:
Originally Posted by Wyldeshot
OP. Did you ever figure this out?

I pretty much have the exact situation. I have a 12fv Savage. Went from 26” to 20” and put in a Bell and Carlson stock. Accurate is all over the place with the suppressor on. Going back to the range this week to shoot without the suppressor.
OP hasn't been here in 12 years and never posted outside this thread so you probably won't get an answer from him.

However, my first thought for your setup is that you have too many changes going on at once (or at least you didn't specify if all these changes were at once).

I would remove everything that is new, go back to the original gun with the original stock and see if it shoots with just the shorter barrel.
If so, does it shoot if you change the stock?
If so, does it shoot when you add the suppressor?

Only change one thing at a time (including ammo) or you can't know which variable is causing the issue.
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Old January 17, 2023, 10:15 PM   #13
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oops, my bad, forgot to look at the OP post date and realize how much time had passed.
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