10 FCP-SR POI issues

[AZDRT]

New to the forum but looking for input from others with a 10 FCP-SR or similar heavy barrel rifle.

So I picked up a 10 FCP-SR about 2 months ago. In stock form i found some ammo it likes and can make one large hole with 3 shot groups at 100 and 200 yards.

The "issue" i am having is that if I put a muzzle brake or a suppressor (direct thread) it shifts my POI 10" up and 6" left. Same results for both muzzle devices.

I am used to seeing a suppressor drop the POI by roughly 2" with othe rifles, so I am concerned that while I have not seen any signs of striking the brake, or a baffle/endcap strike, something is going on that this will likely end up happening.

With heavier barrels is this drastic shift of POI normal, or do I have a valid reason to be concered?

I bought this rifle to use and hunt with a suppressor (legal in my state), so if this is not normal, getting rid of the gun will really be my only choice.

The brake used was a SiCo 30 cal ASR brake, and the can was a direct thread of a friends, i do not remember which one of his it was. I am still waiting on my paperwork to clear on my rifle can, so used his to see what the POI would be.

Same can was used on my 6.5 creed bolt gun and his 308 AR10 with the expected 2" drop.

So, is this normal for a heavier barrel, or is my rifle fubar?

[darkker]

There is no, "normal"; just different.
So every rifle will have its own harmonics. The way the barrel whips and waves as the explosion is happening and the bullet is traveling down the tube. Each barrel will have slightly different stresses and contours, if they put your barrel in the vice to bend it straight; that's another set of stresses that affect the harmonics.

So now, you know that your barrel can group, so it's fine. So you hung a weight on the end of your barrel and it reaffirmed the above, that you have a barrel that is different than another; and you want to know if it's FUBAR??!!
Inspect your brake for contact. If there is none, then you get out your dope book and write down the POI differences for each load and device on/off. Or simply leave it on and forget about it.

[Robinhood]

It is possible that the bullet is not striking the bore of the brake but it may not be even clearance all the way around. Check the barrel and the brake for burrs or proud metal on the mounting face. Check the Brake for concentricity. Check both the barrel and the brake mounting face for perpendicularity with bore. If all is OK then darrker's explanation covers it.