I bought a new Silenceco Harvester 338 suppressor. It makes every gun I put it on shoot 8-12"s low and 4-5"s left. I can't believe this is normal. I have a Magneto Speed chronograph and it affects some of my rifles accuracy but nothing like this Harvester. Dealer says just adjust and and shoot it. If I have to adjust that much to make it accurate at 300 yards, what will I have to do to make it accurate beyond that. Need some advice on what to do.