What are my options if a want to lose the adjustable stock for a full length non-adjustable stock? Has anyone had any luck with a ready to go drop in swap?

You use a rifle length AR tube and stock, but retain the stock carbine buffer and spring , then use a spacer sold by S&W to take up the difference in length so things stay in balance!

Ok thanks for the primer on the mechanics, but what brands and models have people used to do this. Looking for options from what other M&P !0 owners have used. Some of these rifles are proprietary in their aftermarket parts application.

I am, I guess, a bit of a Magpul fanboy. So, unsurprisingly, I went with Magpul's PRS (Precision Rifle Stock) butt-stock to replace the factory adjustable butt-stock. I prefer the PRS over the factory adjustable butt-stock.

I changed out the receiver extension (also called buffer tube), buffer, and spring. I used the Aero Precision M5 Riffle Kit, which includes a rifle length receiver extension, a riffle buffer (heavier at 5.1 oz vs the 2.9 oz of the factory carbine buffer), and a rifle length spring.

After some initial trouble with SOME ammo, my initial thoughts were that I did not hit on the right combo for the butt-stock. Turns out, it was a lube issue with the bolt, not the replacement parts. Don't let this "proprietary" talk put you on unsure footing like I did. No need for a spacer when installing proper rifle length components.

My M&P 10 shoots really nice - I am the component that needs to be improved, and the soft recoil the gun now has will enable me to isolate, and improve upon, my short comings a little bit easier.

Again, the Aero Precision M5 Rifle Buffer Kit, was all I needed.

__________________
Thank God

The simplest solution is to get the Magpul Fixed Carbine stock. It will fit your current RE, is very affordable and light weight. You can also get a thicker butt pad. This is the route I went for my Big Smith

I am not sure your stuff is in length and travel spec for this gun if it is AR15 stuff. The bolt on a .308 must travel further which is why the stock tube is proprietary and longer. God only knows about spring rates?

That is the point!!!! Once the mechanics are correct, you may use whatever standard AR rifle stock you want on an AR tube!

The Aero Precision M5 Riffle Kit is for an AR 10.

__________________
Thank God

I installed a DPMS A2 stock on mine today I got from midway USA. Changeover took 15 minutes. You'll need the spacer like was mentioned.

I picked the A2 because it matches my 20 inch bushmaster and I'm comfortable with the length of pull over the magpul fixed length carbine stock. The magpul would be too short for me (I'm a big guy.)

Brownells now sells the spacer: SPIKES TACTICAL - AR-15/M16 BUFFER SPACER