Hi All, when fireforming once fired brass from another rifle with a larger chamber I FL size until I can just close the bolt with a slight resistance.Now,I never shoot full house loads in my old military rifles so I fireform using a "medium"chargeof 10 grns Unique under a 180 grn boolit seated out to just engrave the rifling in my #4 Mk1.Then I,ll use 12 or 13 grns for my shooting loads,same boolit wt. These shooter loads chamber easier than initial sizing???.Am i not using a warm enough F/F charge?They shoot fine.Then I neck size only and they shoot likewise.What,s the collective thinking?If it aint broke,dont fix it,eh? Thanks,Mike