i put mine on a couple days ago and went to the range and it wouldn't hold open after the last shot anymore ***?
The cause of the bolt not staying open with the MAD installed on your 15-22 is the MAD ARM is rubbing on the front of the trigger area of the lower receiver; this little bit of friction is not allowing the bolt catch to full pivot to allow the bolt to remain open after the last round is fired. All you need to do is straighten the flat part of the BAD arm a little more.
OBTW - Adding wood jaw (maple or poplar or any closed grain hardwood will do in a pinch) plates to a vise will prevent marring the finish on the bad. If your vise does not have removal jaw plates, the attach the wood jaws with double sided tape (carpet tape does a good job and isn't expensive).
You need to bend the arm about 1/8 -3/16" to fit inside of the lower receiver area. Mount the BAD in the vise a use a non-metal hammer... rawhide mallet, dead blow, plastic faced ball pen, etc. Lightly and slowly hammer the arm and then check to see if the BAD fits inside the trigger area. If it rubs then remount it in the vise and give it a few more whacks. When you think you have straightened the arm enough, then attach it to the bolt release lever tab, and insert a EMPTY MAGAZINE, and pull the charging handle, the bolt should stay open. If the bolt closes, you will need to bend the BAD arm a little more to ensure you have enough play for the bolt catch.
I've got BADs on both my 15-22 and my AR-15 carbine. I've used both rifles in tactical courses... no problems. I know cops (LEO and Fed) and snake eater (spec ops types - CCTs, Delta, and SEALs) who do use the BAD too.
A lot of stuff can seem gimmicky, but that doesn't mean it is gimmicky. Over the years I've seen a lot of stuff attached or stuck on ARs by both mil and civ operators....Putty and pink bubble gum! in the space between the trigger guard, lights attached with hose clamps to the barrels. All of it may seem gimmicky to someone, but the operators were happy with the "modifications". I would gladly have any of those guys on my side in a fire fight, anywhere, anytime. I could make a list of things that I would call gimmicky too, but what the hick. If it works; cool, no skin off my butt. So I guess using condom over a barrel to keep rain, mud, or crap out of the barrel is gimmicky too. t works and has kept crap out of barrels on combat rifles (M16s and CARs), my hunting rifles, and even my .54 caliber black powder Hawkins for elk hunting for over 35 years. One size fits all!
Aim small,
tat