I am going to pick up an M&P 15 sport. I think I may want to replace the pinned m-4 stock with an ace stock. I located some youtube videos for removal of a collapsible stock, but I can't seem to locate a video on removal of a pinned stock. Does anyone have a reference for me? Will I need a special tool? Any input is greatly appreciated.

I layer my ar on the carpet used a screwdriver (flathead) put it in the notch on the castle nut and smacked it loose with hammer. There is a tool but I wasn't wasting money on it. If u need help and local to Jackson pm me

That's where I'm confused. Do I have to remove the buffer tube? The ace stock seems to come with a piece of foam that slides right over the existing buffer tube. Do I need a new buffer tube?

New buffer tube buffer and spring. Pkfirearms.com sells a complete set up for 114 plus shipping it's everything you need

That's where I'm confused. Do I have to remove the buffer tube? The ace stock seems to come with a piece of foam that slides right over the existing buffer tube. Do I need a new buffer tube?

 

The foam goes over the stock tube itself (not a buffer tube).

Thanks. I called S&W and they were very helpful and told me the same thing you guys did -- need a new buffer tube kit. The guy also mentioned that the castle nut is staked and it sounds like its a PITA to wrench that thing off of the lower. I think I will probably take it to a gunsmith to do the install. I can't imagine it would be all that expensive. Or I may just decide to leave the thing as is. Not sure that I want to spend another $180 bucks to install a new stock on a $600 rifle.

Shouldn't need a gunsmith. If the castle nut is staked it's removable - but you may need some tools and some torque to get it off.

http://www.m4carbine.net/showthread.php?t=54794

a castle nut spanner/wrench? you wll need a new tube buffer and spring if moving form a pinned collapsable that is set up on and actual carbine length buffer tube.