The AR 10 takeDown pin detent spring is verticle and retained by the pistol grip, not the buttstock like on the AR 15. You won't have to worry about it if all you are doing is changing the buttstock.

The buffer tube (reciever extension) is really freaking torqued on tight. MilSpec torque is 35 to 39 Foot Pounds. It may be difficult to get loose. It is not reatined by the buffer detent. Be carefuf not to lose the buffer detent as you unscrew the buffer tube.

The milspec torque on the lock ring is only 38 to 42 INCH pounds.

I just went the other way- colapsable stock to A2 stock.

Have Fun
Stev A.