Recce 7 Question - 300 Blackout

Just pick up my suppressor and installed it yesterday. Removed the original flash suppressor and put Griffin taper mount on. The first time I left the crush washer on and the shims and hand tighten the suppressor. Was able to shoot it yesterday and POI was way, way, way off. I research a bit and found a forum that said some suppressor manufacturers recommend not using crush washer. Anyone know whether to leave the crush washer on or remove?
Also, could that make the POI shift that much?

You should have received a shim set or peel washer to “time” the brake. Don’t use anything else or it could affect the performance. It isn’t necessarily the reason for the poi shift though. Some suppressors just shift.

thanks!