Magazine Modifications:
To modify a standard mil-spec. 30rnd. magazine for reduced capacity you will need the following parts;
1. 1x
complete 30rnd. magazine [the floorplate and follower type doesn't matter] $15.00/ea (MidwayUSA occasionally sells
packs of 4 in a leather pouch for about $50.00)
2. 1x
"10rnd double stack magazine" floorplate $4.00/ea
3. 1x
"10rnd double stack magazine" safety $4.50/ea
Tools required:
1. Angle Grinder with thin kerf cut-off blade for metal (a hacksaw might also work, and a metal cutting bandsaw would be ideal)
2. Measurement Tool (I used calipers, but the measurements needn't be precise so a tape measure will suffice)
3. Permanent Marker or scribe
4. Wire Cutters (I used a pair of side cutters, but diagonal cutters, side-cutting needle-nose pliers, or most anything else capable of cutting steel wire would work)
5. Wire-Wheel or Sander (optional; for removing the burr left on the magazine body after cutting)
6. File (optional; for cleaning up the groove cut in the magazine body)
Instructions:
1. Completely disassemble the magazine by removing the floorplate, magazine safety (remove this from the spring), spring, and follower (remove this from the spring).
2. Measure and mark the magazine body for cutting. Mark the rear of the body at approximately 6-3/8in. from the top of the notch for the BHO (the part of the magazine that houses the actuator for the BHO {which is part of the follower}). Mark the front of the magazine at approximately 5-3/4in. from the top of the magazine (not the feed-lips, but the flat area at the very top of the front/center).
4. Mark the magazine from front to rear on each side connecting the two marks that you made on the front and rear of the body.
5. Cut along these lines using the angle grinder/metal cutting bandsaw/hacksaw. Note that you should be left with a remnant approximately 2.3"x1.8" depending upon the kerf of the blade used to cut the magazine; if you cut too short you will not be able to load 20 rounds into the reassembled magazine.
6. Using the wire-wheel or sandpaper clean up the burr left on the bottom of the magazine.
7. With the angle grinder or other suitable metal-cutting tool, cut an approximately 0.1in. wide notch on both sides of the magazine starting at 0.15in. from the end of the magazine and terminating at about 0.25in. This notch needn't be deep, it just has to hold the new floorplate securely in place (if you cut too deep you will compromise the structural integrity of the magazine, you just need to cut the folds that extend outward from the body).
8. Clean up the notch with the file as needed.
9. Cut the magazine follower at about 1.33in. in the front and 1.76in. at the rear (both are measured from the flat part at top, not the "bump").
10. Snip the magazine spring leaving 17 loops (length is approximately 14-14.5in. uncompressed).
11. Reattach the spring to the follower and new magazine safety.
12. Insert the follower/spring/safety assembly into the magazine body.
13. Slide the new floorplate onto the bottom of the magazine.
14. Repeat steps 1-13 as necessary for additional magazines.
15. Sit down and watch the Olympics wondering why they never televise the shooting events.