Mauser Magazine modification: how to feed your Mauser a "Swift" diet.
I was working on a M98 Mauser chambered in the iconic .220 Swift. You may wonder why someone would rebarrel a M98 Mauser action to a shorter, smaller diameter cartridge only to have feeding and chamber jamming issues while striping a fresh round from the magazine. This rifle in particular was a large ring military action with a fresh .220 Swift barrel. When the magazine was filled the bolt would push the rounds back and forth while being cycled. An overly large magazine space for the smaller cartridges caused them to become jammed in the magazine as some cartridges would be pushed forward while others would be pulled rearward with the top cartridge occasionally popping out of the feed rails. This is a common issue when the magazine is sized for a cartridge the size of a .30-06.
Why not use a short cartridge follower conversion kit? While that is an option, I wanted this rifle to feed and chamber .220 Swifts smoothly every time. With various countries manufacturing Mauser actions and with minor fluctuation in tolerances between them there would be no way to be certain a conversion kit would be an easy fix.
On the bench I loaded dummy cartridges in the magazine and observed how they fed when stripped from the follower. As the cartridge was pushed forward there was not enough upward angle to position it for a smooth entry into the chamber. What I needed was to angle the follower to help point the cartridge into the chamber.
With the follower removed, I filed a taper angle to the left side top rail of the follower top that contacts the receiver left feed rail. The follower measured 0.368" on the back edge and 0.300" on the front edge. I removed 0.168" of metal from the front edge while tapering an edge to the rear of the follower. This was enough to start the cartridge in at a good angle for chambering while pushing the bolt forward.
This fix worked for single round feeding but I wanted reliable and smooth function from a full magazine. I needed to determine what length to cut the follower to. This .220 Swift barrel had a 1:12 twist and 55 grain bullets would be the heaviest used. I measured factory cartridges with 50 and 55 grain bullets and settled on an average cartridge overall length of 2.600" and allowing some extra space to prevent jammed cartridges in the magazine. This measurement would determine that I needed to cut 10mm off the follower to make a full length cartridge bed for the modified follower.
The cut was made slightly ahead of the back edge of the follower because I would weld the back piece back on. Once welded back together, some filing, shaping, and polishing of the shortened follower fit the desired cartridge length perfectly.
The magazine well needed a block to fill the gap created by modifying the shortened follower. I used a piece of black nylon measuring about 45mm x 17mm x 21mm. Because all Mausers have slight differences in bottom metal, this block must be hand fitted to the individual metal. With a belt sander, small amounts of material are taken off while test fitting the block. It's OK to make the block fit the sides of the magazine snug, however, the block should allow the follower to move freely through full travel without any binding. A final smooth polish to the follower cartridge face side of the block will ensure cartridges slide freely against it.
The block must be cut to correct length to allow a snug fit from the receiver inner feed rail stop to the removable bottom metal. Work slow and test fit often for a perfect fit. The next step of block fitting is opening up space for the bolt to pass over while still keeping the cartridge held forward while on the follower. A Dremel tool with a drum sander makes quick work of this task. Again, use plenty of trial fittings and remove small amounts of material at a time. Once fit, the bolt should not bind anywhere as it passes over the magazine block while also having the cartridge head stop against it.
With the block and follower made, a correct size magazine spring will need to be selected. I have quite a pile of left over magazine springs to dig through when searching for a favorable donor, one good reason to keep old gun parts. A magazine spring is selected by measuring the space from the front side of the new block to the front inner side of the magazine well. With the spring compressed, the center leaf length needs to fit in the magazine space with plenty of free movement. The leaf that fits into the follower spring clip will need to be shortened and have the narrow side section filed back to allow full engagement into the follower groove while allowing the rear portion to be held against the follower stop.
Test fit the spring by pushing the assembled spring and follower down into the magazine. When binding is noticed, shorten the leaf spring that fits into the floorplate. When this spring section is shortened it allows the magazine spring to pivot the follower forward, allowing free travel through the magazine. This should result in smooth feeding cartridges when fully loaded into the magazine along with a good-feeling push feed when stripping a fresh round.
Modifying the follower and associated parts to accommodate a smaller cartridge will improve the overall function to strip and feed rounds smoothly. Attention to small details like this will make customers return for other work and the compliments spread by word of mouth are the best public relations you'll ever receive!