Would help to know which model butt stock.




On the above unit, you can see the cross pin that holds the lever detent pin collar in place (buffer bumper is pointing at it), and if needed to fine tune the butt stock to the receiver extension, you can drive the roll pin out of the detent pin to adjust the bottom collar nut up or down on the detent pin threads on to adjust the pin correctly.

Hence if the release lever is not releasing the detent pin from the receiver extension detent positions correctly, then the collar nut threaded up another half wind or full wind solves the problem to allow the lever to fully release the detent pin from the receiver extension groove detent's.

If on the other hand, the butt stock is not holding fast during say recoil, then the collar nut can be spun down to allow the detent to engage the receiver extensions a touch more in the lever at rest position.  


As for adjusting the  lever detent collar nut, pull all the way down on the lever to dray the detent pin all the way into the butt stock (not just cam'd) and pull the butt stock off the back of the tube.  Now butt stock loose, drive the roll pin out, then holding the index pin via the inside of the butt stock, thread the nut 1/2 more wind upwards on the detent pin threads, then give the butt stock a try before reinstalling the roll pin back into secure the collar to that thread position on the levers detent pin threads.