A friend of mine has just returned from his first trip to Africa and, as all such hunters do, is now walking around with his eyes fixed on a distant continent, plotting how to get back. (The place does get a hold on you.) He was hunting for plains game, and brought along a .300 Winchester Short Magnum, loaded with Swift Sciroccos, which performed peerlessly. However, he experienced a problem that comes up very often, particularly with short-necked cases like the .300 WSM–the bullets slipped forward in the case and one of them eventually jammed its little meplat in the rifling causing all sorts of problems.
If you’re not aware of this when it happens, you’ll yank the bolt back and the bullet will come out of the case, spilling powder everywhere and leaving you to find a cleaning rod to drive the slug out. It happened to me on an elk hunt in Colorado, using 250-grain .338 factory loads with a very long, then-experimental bullet. I barked and roared like a berserk baboon.
Most of the time, bullet slip is caused because the case neck is short, or not resized enough, or you got case lube in there and didn’t remove it. What completes the tragedy is loading the magazine and firing only the top round, time after time. The bottom cartridges stay put, and the force of repeated recoil causes the bullets to creep forward, much as it does in an inertia bullet puller.
Bullet creep is aided and abetted by the practice of neck resizing, which has no place in big-game ammo, and seating the slugs so that they are the width of a frog hair from the rifling in order to get that last .005-inch of accuracy. When loading hunting ammo, I full-length-size everything so the necks get as good a grip as possible on the bullets. I seat all bullets to SAAMI spec; I want the damn cartridges to cycle, not to produce the last possible bit of accuracy. I run a Q-Tip doused in lighter fluid around the inside of the neck. You’d be amazed at the gunk that comes out.
In 1987 I went to Zambia with a .458 and handloads whose bullets slipped chronically. It got so bad that I had to borrow ammo from the PH. If he had not also used a .458 I would have been SOL.
Watch this stuff.