Monday, November 15, 2010

.45-70 Mosin Magazine conversion, Re-weld

As discussed in the theory post below. Here are the data from the re-weld of the Mosin magazine, for the .45-70 conversion.

To facilitate re-welding, a simple re-weld jig was manufactured from an old brass punch. The punch was milled to size, the main dimension being the width at the rear of the magazine well, the minor dimension being the width of the rear section  minus one half the width of the front section. The middle section of the magazine side wall was cut out. Only one side at a time was re welded to preserve geometry and spacial relation of the parts. The middle section of the magazine side wall was cut out, using the "dimple" as a guide.

Figure 1: Right side of the magazine set up for welding. The middle section has been cut, and tack welded to the front housing. The minor dimension of the re-weld jig is then used to tack weld the top an bottom of the middle section at the cut line. Note that the gap is quite large, about 1-2mm, since a small amount of the cut out side plate is overlapped with the front of the housing. Having a brass jig is critical for spanning and filling in the gap with weld!

Figure 2: Left side being set up for welding. The middle section has been cut, and the jig inserted, the major dimension of the jig is used. The left side plate is then welded in and ground smooth. Note that the distinctive "dimple" that creates the stepped width of the Mosin magazine well, has effectively been moved to the front of the assembly, using this procedure.
Figure 3: The right side is finished next. Use the brass jig to support the side wall for the re-weld. Note the ground tack weld on the top.

This procedure is effective, and allows the Mosin magazine to accept and cycle the .45-70 cartridge unhindered. It should be noted that a minor amount of warping was observed. This is most likely due to lack of welding experience and an incorrect approach. Next attempt the weld bead will be run in small sections, alternating between the front and rear beads.

1 comment:

  1. I'm throughly enjoying this build! As far as the warping, your on the right track. It's like auto body work, you don't run beads, but instead do a series of tacks, letting things cool as much as possible. Keep making tacks untill you've filled the entire area. The hardest part (especially for me, lol) is not going too fast, it's one of those things where the slower the better. -Sam