Thread: How short on a 303?

Originally Posted by Driverman

Use an o ring to hold the case against the bolt headfor the first firing. Neck size from that point on. I shoot 220 grain cast at 1800fps and don't size the neck at all. Most 303 have a .314 bore or bigger and using a 308 projectile will not be accurate.

Get the headspace checked if an O ring will let the bolt close you have a headspace problem, .303's headspace on the rim not the shoulder