Tinkering With a Short Mag

Last week a customer brought in a Winchester M70 bolt action rifle chambered in .25 Winchester Super Short Magnum. The .25WSSM has a short and wide case, and basically duplicates .25-06 ballistics but with an action almost an inch shorter.





The problem, he said, was that the bolt was skipping over the rear of the cartridge case and not chambering the round, resulting in an empty chamber and a "click" instead of a "boom". Not good.

The first place to look with almost any gun problem is the springs. In this case, it made sense to check the magazine spring, since it's responsible for pushing the rounds upwards and having them ready to be loaded into the chamber.

Oddly enough, the spring felt fine. It felt a little mushy towards the front of the magazine, but very strong towards the rear. The thing about leaf springs (it looks like a "Z" from the side) is that they will sometimes be inconsistent, and the strength towards the back end made me think that it wasn't the problem.

Next we checked the follower, the little platform in the magazine where the round sits. It looked to be a little short, but not short enough to cause the problem by itself. For some reason Winchester's quality control has slipped a little recently, and magazine bodies are no exception.

By this time, I'm baffled. Having no .25WSSM inert rounds or action dummies laying around (it's not a common round yet), I took the firing pin out of the bolt and used a couple of live rounds to check the feeding for myself. Any time you have a live round near a firearm and you're not planning on firing it, take the firing pin out to prevent any chance of it going boom. I have been around guns fired indoors unexpectedly, and it's unpleasant.

After loading the magazine and running several rounds through the action, I found the problem. The rounds fed fine if they were feeding from the right side of the magazine, but coming from the left side, they left the magazine feed lips at a bad angle and the front of the round nose-dived towards the front. Pull the bolt slightly back to fix this, and it skips over the round entirely. Problem identified. I pulled the magazine box out of the rifle, and immediately noticed that the magazine feed lips were completely different on the right side and left side. Reasoning that they got it right (no pun intended) with the right side and wrong with the left side, I carefully bent the left side lips to match its twin. I put the rifle back together minus the firing pin, and checked the action. Perfect cycling from both sides.

Total time to fix, after the head scratching? Five minutes with a pair of sheet metal pliers.