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.

Thursday, November 11, 2010

Milled Yugo AK reweld

To practice welding, and in anticipation of continued mosin work. A rewed of the milled receiver Yugoslavian M72 RPK, in pistol form. This method was introduced on, by "VZ-58". This is a twist on his work, using his reweld plates. Front is a receiver stub, rear is a pistol trunnion.

Harbor Freight model 98233, argon shielded TIG was used for welding.

The magazine conversion, theory

Above are two candidate magazine wells. Top one is Polish in origin bottom is a Russian Izhevsk. Surprisingly the Polish magazine is narrower, and will not accommodate the rim of a .45-70 cartridge. The Russian magazine is wide enough in the rear, and middle sections to fit the .45-70 round.
From the above picture it clear that for the Russian mosin magazine only the front third needs to be opened up, to loading. Voland believes that the latter is best achieved by cutting out the front 3rd of the magazine sidewall, and rewelding it to fit the .45-70 cartridge (See figure below).