Tight grip fit is pretty normal. Warm the grip with a hair dryer and a touch of lube helps. The tight Pmag problem is fairly common also. I had one Pmag that was tight in every AR I own and a few that were tight in only one or two AR's. I've had Pmags become tight after a year or more of being in service.
D&H GI Teflon coated mags with the latest followers are $9, stock up.