I have the Express SuperMag as well, and I recently added an Uncle Mike's sling stud kit. I hate those loop style slings that are always slipping off in the field.
If you drill the rear stock for a stud, take your time. I actually used four different bits to get mine right.
1. I used a tiny 1/16" bit to drill a pilot hole. Easier to control and make sure of a straight hole. You only have a small ridge of composite material inside the stock so you need to be straight (as well as perpendicular to the stock).
2. Then I used a larger bit (3/8" I believe, same diameter as the big end of the sling stud) to take out a shallow amount of the composite, leaving me with a flat mounting surface for the sling stud. I just went slow and shaved off a little at a time. You don't want this hole to go too deep! It also helped here that I used Black & Decker Bullet bits. Left a flatter surface than a regular convex bit.
3. I followed the directions on the pack from here--drilling a hole for the shank to a certain depth and then a smaller hole for the threads the rest of the way.
A drill press would have been useful, but I don't own one. Instead, I simply wrapped the drill bits with lots of electrical tape to prevent myself from drilling too deeply on the second and third holes.
When threading the stud, again go slow. Thread a little at a time and then back it off until you can snug it up tight. Don't try to crank down on the stud once it snugs up. The composite won't compress like wood, and it can crack. Believe me, I know. On my first attempt, I had everything drilled and was tightening up the stud. Just needed one more quarter turn to line up the holes in the stud. Although the stud had already tightened up, I thought I could get that last little bit to go without taking off any more composite. So I cranked it pretty hard, and the stock cracked along the mold line. Wound up costing me $30 for a new synthetic butt stock on eBay. In retrospect, I should have used my Dremel and little grinding wheel to take off just a bit more of the synthetic composite on the flat mounting surface. That way, the stud would have had room to go another quarter turn. Oh well, live and learn. The next time I attempted the installation, I got it right.
Why can't Remington simply charge $10 more and put these on in the first place--especially for guns they market as turkey hunters???
