Look for a sling mount to fit the tube. Like to buy one for a decent price that i don't have to modify.

Midwest Industries Rear Sling Mount Adapter Ambidextrous Loop AR-15 Carbine Aluminum Matte - MidwayUSA

This is the best rear mount I've found for the 15-22. You just have to remove the butt stock and slide this over the rear "buffer tube" and tighten the bolt down. Easy. It's tough and extremely well made. No modification required. Fits nice and tight so you'll never have to worry about it moving.

any reason why nobody uses the clip on the bottom of the stock? never tried to put a sling on it, just wondering.

+1, MI Rear Sling Mount Adapter.

The bottom sling mount has since been removed.

Here's how the slot in the stock works with a Blue Force sling:






Inexpensive rail mounted swivel. This one is quick disconnect.



-- Chuck

Went with the Midwest Industries sling plate adapter. The first two shown on their page work perfect. Then went with the Magpul RSA. Mounted it @ the very front left side. Then went with the Magpul MS2 sling to have options. Highly recommend all of those products.