Picked up a short action DBM, had a group buy on snipers hide for $95 shipped. Had some time to install it yesterday. Used a milling machine and still took me 4 hours or so. Pretty pleased with the results.
Then I had the issue of no 5rd mags available in 223 from AI. The 10 round poly mags are only $33 at Triad Tactical in the US so I decided to get some of those and try modification.
The steps I did are as follows:
1) grind the spring at the bend as shown in the pic
2) straighten the leg of the cut pc, grind the sides narrow and drill a hole to match the detail in the cut off pc
3) Grind (I used an industrial disk sander) 1 3/8" from the bottom of the mag body (scribe a line parallel to the bottom of the mag for ref and grind to the line)
4) Using a file or milling machine machine a step onto the front of the mag to catch the front end of the retaining lip on the bottom plate. Use a file to radius the corners or the plate will not slide back enough to catch the lip.
5) Grind or file a bit off the length of the bottom plate, now that it slides farther on the body it sticks out at the rear.
6) Drill and tap a hole through the bottom plate into the back wall of the body, the wall is 3/8 thick. I used 10-24. There is a void in the wall in the center, it did not affect the holding ability of the screw. Take the bottom plate off and open the hole to clear the screw diameter. Use a file to slot the hole for the lock button on the bottom plate or it wont engage.
The result is good. I need to switch to a stainless screw or even a flat head. I did 2 and I could jam 6 shells into one of them, I just ground a little more off the length of the body. Ready for coyote hunting with the 5rd mags!


Then I had the issue of no 5rd mags available in 223 from AI. The 10 round poly mags are only $33 at Triad Tactical in the US so I decided to get some of those and try modification.

The steps I did are as follows:
1) grind the spring at the bend as shown in the pic
2) straighten the leg of the cut pc, grind the sides narrow and drill a hole to match the detail in the cut off pc
3) Grind (I used an industrial disk sander) 1 3/8" from the bottom of the mag body (scribe a line parallel to the bottom of the mag for ref and grind to the line)
4) Using a file or milling machine machine a step onto the front of the mag to catch the front end of the retaining lip on the bottom plate. Use a file to radius the corners or the plate will not slide back enough to catch the lip.

5) Grind or file a bit off the length of the bottom plate, now that it slides farther on the body it sticks out at the rear.
6) Drill and tap a hole through the bottom plate into the back wall of the body, the wall is 3/8 thick. I used 10-24. There is a void in the wall in the center, it did not affect the holding ability of the screw. Take the bottom plate off and open the hole to clear the screw diameter. Use a file to slot the hole for the lock button on the bottom plate or it wont engage.

The result is good. I need to switch to a stainless screw or even a flat head. I did 2 and I could jam 6 shells into one of them, I just ground a little more off the length of the body. Ready for coyote hunting with the 5rd mags!
