Originally Posted by
Adam Helmer
I have too many .303 rifles and carbines and each is reloaded for with all ammo specifically reloaded to each individual arm. I label each box of reloads so I keep it straight. The reloading die makers put bad info in their .303 reloading die boxes when some say to run the sizing die down to the shell holder and then GO down another quarter turn! Wrong.
The .303 headspaces on the rim but must be reloaded to headspace on the shoulder for long case life. Since 1958, I use a light load for first firing to fireform the case in each arm. On the next loading, I set the resizing die only enough to permit a slight crunch fit and record on the label how far I backed off the sizer above the shell holder for each specific arm. I have .303s backed off a quarter turn, others - one half turn and one old MkIII backed off 1.5 turns. I get very long .303 case life.
Adam