Is this POI shift somewhat normal?

[bellavite1]

I have a Griffin Optimus 9 suppressor.
I just got my .308 Rem 700 SPS Tactical threaded to play with it.
Muzzle device is a Minimalist Flash Hider, also form Griffin Armament.
I have noticed a fairly large POI shift, 6 MOA in elevation and about 1 MOA in windage between suppressed and unsuppressed.
Very repeatable, thank God, since I shot groups alternating 1 shot with and one shot without, and although the groups sucked (wind gusts plus frankly I was getting quite frustrated at this point), the shots grouped nonetheless.
Normally I get about 1/2 MOA out of this gun, so please excuse my groups...
Anyways, no baffle strikes or anything.
Just got a call from the gunsmith that threaded the barrel (or soon-to-be ex-gunsmith) trying to tell me that there's copper fouling and chamber erosion and all kinds of stuff...
Now, unless I am missing something, that would not cause such a consistent POI shift, it would just make the rifle less accurate.
Top left group is suppressed.
Center group is unsuppressed.
Is such a consistent but large shift somewhat a possibility or does it mean something is wrong?
I can just zero for suppressed and call it a day I guess...

 

[Kadams1563]

Thays a lot compared to what I see with my Omega with the ASR mount, the Keymo mount, and the area 419 mount.

 

[Landon4]

Is that at 100yds

 

[nn8734]

Assuming that’s at 100m or 100y - If the shift is consistent in terms of amount and direction and group size is also consistent then record the shift in your DOPE book and move on. My Mk11’s POI shift from zero w/the can vs without is similar.

Nothing to worry about.

 

[KnowNothing256]

+1 for account for it and shoot it. I personally prefer to just zero suppressed if I’m gonna run the can.

 

[bellavite1]

Yup, 100 yds, don't hold it against me...

 

[bellavite1]

Update:
After checking with a different shop, it turns out the threads were cut out of spec.
Barrel had to be cut 0.60" and re-threaded, but what a difference:
What you can see in the pic is 10 shots from cold bore, 100yds, the first five suppressed and the remaining unsuppressed.
No POI shift that I can tell.
The flier was totally me...
And that, my friends, is the difference between a butcher shop and a Gunsmith.

 

[B y r o n]

Glad to see you got things resolved.