Suppressor changing point of impact by inches

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12-08-2018, 08:38 PM
Russian 22.

Suppressor changing point of impact by inches

Shot my ar15 today. With the suppressor on to sight it in. I then shot it without as the suppressor was hot. The point of impact went up 6 inches or so high.

Any suggestions on what would cause this. I was shooting Barnaul but I don't think it'd have anything to do with it.

Cheers.

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12-08-2018, 08:48 PM
Tommy

You should probably mention this was 6" at 25m..
12-08-2018, 09:03 PM
systolic

What did you expect to happen?

Adding or removing anything from the muzzle is always going to affect point of impact.

Sometimes a little, sometimes a lot.

In this case, quite a lot.
12-08-2018, 09:15 PM
Clint Ruin

Barrels move a fair bit with a bullet moving down it . Anything that add/subtracts weight to the barrel will effect how it moves .
12-08-2018, 09:29 PM
Kiwi Greg

Quote:

Originally Posted by Tommy

You should probably mention this was 6" at 25m..

If it was that much its pretty excessive

Heavy suppressor on a light barrel ?
12-08-2018, 09:34 PM
Tommy

Quote:

Originally Posted by Kiwi Greg

If it was that much its pretty excessive

Heavy suppressor on a light barrel ?

Nah it's a DPT on a heavier 223 barrel, short for the profile too. Baffle strike probably isn't an issue either, it's a .30 can from memory. Took it apart and checked for strike.
12-08-2018, 09:36 PM
Max Headroom

You will get a POI change without a suppressor, but 6 inches is a lot at 25m. Only thing I can think of is to try that again with different ammo in case barnaul was an inconsistent batch.
12-08-2018, 09:36 PM
gundoc

2-3" at 100 could be considered normal, 6" at 25 is indicative of misalignment of the suppressor. This could be as a result of poor threading, shoulder damage, bent suppressor, poorly made suppressor, etc. It needs to be checked with an accurate alignment rod before you shoot it again. A very light barrel would not help the situation due to muzzle whip.
12-08-2018, 11:20 PM
Russian 22.

Quote:

Originally Posted by systolic

What did you expect to happen?

Adding or removing anything from the muzzle is always going to affect point of impact.

Sometimes a little, sometimes a lot.

In this case, quite a lot.

I knew it would change but wasn't sure if that much was normal.

Quote:

Originally Posted by Clint Ruin

Barrels move a fair bit with a bullet moving down it . Anything that add/subtracts weight to the barrel will effect how it moves .

True.

Quote:

Originally Posted by Max Headroom

You will get a POI change without a suppressor, but 6 inches is a lot at 25m. Only thing I can think of is to try that again with different ammo in case barnaul was an inconsistent batch.

I have some brass cases fmj at home I'll try.

Quote:

Originally Posted by gundoc

2-3" at 100 could be considered normal, 6" at 25 is indicative of misalignment of the suppressor. This could be as a result of poor threading, shoulder damage, bent suppressor, poorly made suppressor, etc. It needs to be checked with an accurate alignment rod before you shoot it again. A very light barrel would not help the situation due to muzzle whip.

Ok. The shoulder looks fine, the dpt has lasted about 80 rounds of 308 fine so I am thinking that it's ok.

I got it threaded by a machinist friend. He also did my 308. I was going to get a stainless steel blast baffle from Darren so may see if he'll have a look at it. ..

Cheers for the advice.

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12-08-2018, 11:58 PM
gadgetman

Quote:

Originally Posted by Russian 22.

I got it threaded by a machinist friend. He also did my 308. I was going to get a stainless steel blast baffle from Darren so may see if he'll have a look at it. ..

Cheers for the advice.

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Did your friend centre the work on the bore when he did the threading? Make sure it wasn't centred on the outside of the barrel.
13-08-2018, 12:34 AM
10-Ring

On two .308 rifles, one mine and the other my mate's, the addition of the suppressor changes the POI to about 3" high at 100m. Every other suppressor I've seen lowers the POI. Barrel harmonics I guess.
13-08-2018, 03:57 AM
chalkeye

Quote:

Originally Posted by Russian 22.

I got it threaded by a machinist friend.

Did he indicate off the outside diameter, or the bore? Like @gadgetman, I'm leaning towards this cause :pacman:
13-08-2018, 10:06 AM
DPT

If the suppressor is slightly off to the bore that should not really make a difference with the point of impact, if the bullet is touching the baffles that will defiantly cause accuracy issues.
My guess is that the rear bush is touching the barrel on one side potentially bending the barrel inside the suppressor, try removing the rear bush and shooting it, before shooting it make sure the suppressor is a nice fit on the barrel thread and is not wobbling around.
13-08-2018, 10:09 AM
Russian 22.

Quote:

Originally Posted by gadgetman

Did your friend centre the work on the bore when he did the threading? Make sure it wasn't centred on the outside of the barrel.

I will check and get back to you.

Quote:

Originally Posted by 10-Ring

On two .308 rifles, one mine and the other my mate's, the addition of the suppressor changes the POI to about 3" high at 100m. Every other suppressor I've seen lowers the POI. Barrel harmonics I guess.

Quote:

Originally Posted by chalkeye

Did he indicate off the outside diameter, or the bore? Like @gadgetman, I'm leaning towards this cause :pacman:

I will check.

Quote:

Originally Posted by DPT

If the suppressor is slightly off to the bore that should not really make a difference with the point of impact, if the bullet is touching the baffles that will defiantly cause accuracy issues.
My guess is that the rear bush is touching the barrel on one side potentially bending the barrel inside the suppressor, try removing the rear bush and shooting it, before shooting it make sure the suppressor is a nice fit on the barrel thread and is not wobbling around.

The rear bush is touching the barrel pretty uniformly on both barrels I use it on. There's barely any gap between the barrel and bushing.

Ok. Will do. Thanks a lot.

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13-08-2018, 10:18 AM
DPT

Quote:

Originally Posted by Russian 22.

I will check and get back to you.

I will check.

The rear bush is touching the barrel pretty uniformly on both barrels I use it on. There's barely any gap between the barrel and bushing.

Ok. Will do. Thanks a lot.

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We give the bushes clearance, about 0.05mm over size, open it up a little so its not touching the barrel.
13-08-2018, 10:20 AM
Gibo

My old MAE 2 tonne suppressor used to cause a 8" poi change from on to off @100
13-08-2018, 10:34 AM
Russian 22.

Quote:

Originally Posted by DPT

We give the bushes clearance, about 0.05mm over size, open it up a little so its not touching the barrel.

Sweet. I have a pipe reamer at work I'll use. Or get the engineers to use the lathe.

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13-08-2018, 04:54 PM
Marty Henry

I recall Browning used to offer a barrel tuner called the BOSS basically a weight that you used to slide up or down the barrel to change the point of impact, any weight or pressure on the barrel will change the poi. Just compare shooting a few rounds normally then resting the barrel on the sandbag and see where the rounds go.
13-08-2018, 05:46 PM
Russian 22.

Quote:

Originally Posted by Marty Henry

I recall Browning used to offer a barrel tuner called the BOSS basically a weight that you used to slide up or down the barrel to change the point of impact, any weight or pressure on the barrel will change the poi. Just compare shooting a few rounds normally then resting the barrel on the sandbag and see where the rounds go.

I've seen rubber rings out on the range.

I texted my mate and he said that it was inside the barrel not outside centered

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15-08-2018, 11:19 AM
Bagheera

Truly 6" at 25 yd ?
Thats too much for barrel flip. Something else must be loose.

My 7mm08 had 10cm change at 100m with suppressor on. Then it went crazy 20 .. 30cm out worse with supp off than on ...
Turned out a scope base screw had come loose and the suppressor was affecting how much unpredictable movement occurred in the mounting. Tightened that one screw and it went back to behaving itself.

Is your gun shooting well with the suppressor off ?
15-08-2018, 01:07 PM
Russian 22.

Quote:

Originally Posted by Bagheera

Truly 6" at 25 yd ?
Thats too much for barrel flip. Something else must be loose.

My 7mm08 had 10cm change at 100m with suppressor on. Then it went crazy 20 .. 30cm out worse with supp off than on ...
Turned out a scope base screw had come loose and the suppressor was affecting how much unpredictable movement occurred in the mounting. Tightened that one screw and it went back to behaving itself.

Is your gun shooting well with the suppressor off ?

That's what the fella helping me reckoned. 4-6 inches.

It's got iron sights.

Yeah it did a good group for someone who's never shot irons before. Will try against sometime and see if it helps

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23-12-2018, 05:01 PM
dudz

I've never experienced a difference of poi with or without a suppressor over 600 mtrs except one time when the thread in the suppressor was very slightly off center. I noticed a tiny indent on the muzzle of the suppressor where the projectile was just brushing against.