Folding Stock Adapter Plug

15-22 Side Folding Stock Adapter – Fixed Stock, Collapsible Stock or Brace
Note: This REQUIRES PERMANENT modification to the lower of your S&W M&P15-22.
DO NOT under any circumstances, attach the upper to the lower while modifying the lower.
Seriously… Do not think about it, entertain it or do it. EVER!!!
Keep the upper separated from the lower until the conversion is complete. They should not even be in the same room.
No kidding. Get the upper out of the building where you’re working.

Make 100% sure that it’s legal in your area. We can not and will not provide any legal advice as to what you can do with the piece of metal in your possession.
There is a difference between a brace and a stock. Be sure of what they are.
For ATF clarification and definitions about what different length firearms are, go to – https://www.atf.gov/file/55526/download
This adapter is to convert the standard S&W M&P 15-22 carbine collapsible stock “receiver extension” (AKA Fake Buffer Tube) that’s molded as part of the lower receiver to a folding stock.
NO OTHER USE IS ALLOWED…DO NOT EVER attach a shoulder stock to a pistol. EVER.

1. Remove the upper from where you will do the work before doing any modification
2. Use a hacksaw to remove the receiver extension. The transition from the round part the stock slides on to the receiver is the most common spot.
3. Use a wood rasp to file the remaining part of the “tube” absolutely flat. Chamfer (edge break) the inside edge so the adapter can seat better.
5. Install the adapter in the lower (Still with nothing in it)
6. Use a 1/8” drill and drill the 1/8” offset hole through
7. Change to a 5/32″ drill and drill the center hole through
8. Remove adapter
9. Drill the center hole through with a 3/16″ drill
10. Install roll pin in the 1/8 hole in the adapter until 1/4” is sticking out from the face
11. Install adapter with roll pin into the Side Folding mechanism
12. Install buffer tube in the usual manner in the back of the folding adapter. There will be no buffer retaining pin and spring since the 15-22 does not use them.
If your new buffer tube does not have (rotational) adjustment for where it stops, screw it into the adapter until it looks right. The hinge needs to be to the left in normal use.
13. Open the adapter with the stock attached and press the adapter into the lower. Ensure the 1/8” pin goes into the 1/8” hole you drilled in the lower.
14. Screw in center keeper screw. Use 1/8” Allen Wrench. Just snug, not too tight.
15. Align stock. Make sure it is straight up and down. Tighten center screw to keep assembly in place. Double and triple check the alignment is good.
16. Install small side screw. This really locks the assembly into place.
17. THEN and only after you have the stock installed can you can reattach the upper.
Do not remove adapter or stock with upper attached. EVER
18. Remove some material from inside the bolt stop for the head of the keeper screw. About 1/8″ (.125 inch) or 3MM