Gents

I got a bit of a head scratcher here. I bought a new 6.5” 500. Well I thought I got a dud. Light primer strikes, even had a squib load if that what you call it. Bullet enters part way into the forcing cone, primer is out of the pocket, cylinder jammed up tight. I get it apart, pull the empty out of the cylinder and the powder falls on the floor. Upon closer inspection it looks like rust. Partly ignited I guess. So I try just shooting primers only, no powder or bullet. I get a psssst not the usual loud crack of a primer going off? I loaded some Federal 210, no problem gun goes off like a champ. I tried the Winchester primers in my Desert Eagle, no problems. Funny this recent recipe is the same recipe batch that worked in a Performance Center 500 I had before I sold it. So I tried the usual tightening up on the main spring screw, it was tight, put a spent primer with out the anvil under the screw to get more of a purchase, but no change. I took the gun to a S&W factory authorized center, they tried factory Hornady ammo, gun worked great. So the bottom line I can’t my new gun to shoot Winchester LRP primers? Any ideas other than the obvious (changing to Federal primers), I got 10,000 of the Winchesters. Thanks