Loading my own for 46 years, never saw this happen before. Loaded a dozen 300 grain Hornady HP's by the Hornady book, a Hornady 450 Marlin case like they used, with a WLR like they used, and a starting charge of 38.5 grains of H4198 like they used with that same 300 that they used. Went to range in five below zero weather, fired 1st shot at 100 yard gong. WHAM, an inch or two above the hairs, nice blast but soft recoil, put another one in, CLICK, opened the action and the shell came out spilling powder inside the action and all over the bench top. Bullet lodged in barrel. How on God's green Earth did the primer push the bullet out without lighting the powder? Tapped the bullet out of the barrel with a wooden dowell once home. Picture of it here attached. Though I heard nothing rumor has it that you don't when only the primer goes off, and I didn't so no mystery there, BUT as can be seen the primer 'did go off' and blackened the base and around the lower outside edges of the projectile a bit. Enough fire and heat and hell from the primer to lodge the bullet in the barrel but not enough to light the powder! Duh, I don't get it. Though it was cold out the shells were not exposed to the cold but for a minute or two when that happened.