I have a question for you, does the brass fired from your rifles have loose primer pockets on the first firing? I have a stock barrel (LW) on mine and it shoots real tight but the primer pockets are loose on the first firing. I switched to an adjustable gas block and it has helped some but not much. I get the loose promer pockets on mild and hot loads with the can on and off. I only use Hornady match brass because I have a steady supply of once fired from bolt guns and it's alot better than Federal. I think it maybe due to a larger gas port size on the stock rifle. I'd bet the GAP rifles have a smaller port size...