To cut the extractor slots, a standard 1/4" x 1/8" broach had to be modified. The standard broach had "shoulders", which made it too thick to use. It was also too wide. In this picture, the unmodified broach is on the left, the modified broach is on the right. The "shoulders" on the unmodified broach were removed by first blanchard grinding them to about .010 oversize, and then surface grinding them entirely off, until the broach measured 1/4" (.250) thick. The surface grinder was also used to reduce the broach's width. Several of the uppermost broach teeth also had to be ground down, in order for the broach to pass through it's respective bushing. These ground teeth are visible in the forefront
of the modified broach (right most in picture).
The broach bushing was inserted into the barrel bore at the front of the receiver. The slot in the bushing was then located in the exact position where the extractor slot must be cut. The broach (see above) was then inserted in the slot and a 40 year old, 100 ton press was used to press the broach all the way down, until the press head stopped on the bushing head. The broach was then removed from the bushing, and a .030 shim was inserted into the bushing slot. The broach was then pressed through the receiver. The shim caused the broach to cut the extractor slot another .030 deep. This "shim and broach" procedure was repeated until the extractor slot was at it's correct depth.
Inside the TSMG receiver, the bolt shank passes through a hole in the front receiver wall, enroute to the barrel chamber. This hole has a countersink. The countersink is necessary for clearance of the radiused portion of the bolt shank, where the shank meets the bolt body. Without a countersink, the radiused portion of the bolt shank will make contact with the receiver bolt hole - and the bolt will not be able to go into battery. The countersinks in the Auto Ordnance receiver nose sections measured .765 diameter. The closest size countersink I could find was .825. Using a "whirley-gig", I ground the .825 countersink to .765 diameter.
After grinding the countersink to .765 diameter, I needed a way to attach it to a milling machine. So I made this extension from an old steel rod. It's 9" long, just under 3/8" diameter at it's skinny end, and just over 1/2" diameter at it's fat end (actually, it's .650 diameter). The fat end has a 1/2" x 1/2" hole, into which the countersink shank fits. The countersink shank is held in place by a set screw. The .005 brass shim inside the countersink hole (i.e. "the fat end") was necessary because I was too lazy to drill the 1/2" hole first with a 31/64 drill, and then ream it to 1/2". Instead, I went from 1/4" to 3/8", to 1/2" drill bits. Naturally, this resulted in a slightly oversized 1/2" hole (by about .010).
At first glance, it doesn't look like much. But this little chunk of steel and u-bolts did remove the barrels from my parts kits. If you look closely, you can see a brass shim in the barrel grove. Being a soft metal, the brass protected the barrel from being scratched by the steel of the wrench. I used a .015 shim, and had to make the barrel groove correspondingly wider and deeper. Without using the shim, the barrel groove would be 1" wide, by 1/2" deep. The shim increased this to 1.030 wide (.015 on each side of the barrel grove = .030 total shim thickness + 1.000 barrel width = 1.030 total width of barrel grove in wrench), by .515 deep (shim thickness of .015 in barrel groove + .500 depth of groove = .515 total depth). The square "tower" on the wrench top is 1/2" x 1/2". The tower accomodates a standard 1/2" socket extension (4" long). I put a 4' long steel breaker bar over the extension. When the wrench is in place on the barrel, the u-bolts fit between the grip mount and the barrel. Initially, the u-bolts were just a bit too thick to fit between the grip mount and the barrel. I used a belt sander to remove enough material from the u-bolts to make them fit between the grip mount and the barrel.