reloading 308 into 303britt

[22-250hunter]

has anyone else done this b4? im using a 165gr sierra gameking HPBT im using my 30-06 die to neck size the 303 case and deprime iv only made one dummy round no primmer just resizing and seating chambers good and the bullet fit the barrel well i just wanted to get some input b4 i made any to fire!

 

[RT2506]

You need to ask a complete question as to what you are trying to do. If it is trying to shoot a .308 diameter bullet in a 303 British rifle you are wasting your time because the 303 British needs at least a .311 diameter bullet and some need .312 diameter bullets to shoot accurately. The bore of the rifle needs to be slugged to see what diameter bullet you actually need. Slugging is done by driving a .315 diameter lead muzzle loader ball through the bore and measuring between the high spots which is the groove diameter. Use a bullet exact groove diameter to half a thousand larger than groove diameter to get best accuracy.