1st issue this weekend: Shooting a RRA lower with a 6 position stock with a with a Colt 16 inch flat top. BCG is a new Bravo Company group. Had  repeated issues where the bolt failed to lock up after the last round on magazine. Was 1st using Thermomold 20 rd. magazines. Thinking this was the issue, I swapped between PMAGs as well as USGI's with MAGPUL followers and the issue still occured. It was random, but still happening. I was shooting Federal 55gr 5.56 as well as Federal SS109 5.56, 62 gr. I did keep the bolt well lubed with Slip2000.
Any thoughs?

2nd Issue: Shooting a band new Smith and Wesson M&P flat top with 6 position stock. Stock was fully extended and with every shot, the stock would collapse back to either the 5th or 4th position. I checked before each shot to make sure the stock was fully in the slot for position 6. Was using the same mags as well as ammo as above. Any thoughs on this one?

Did you actually pull the stock off the tube? I'm wondering if there was some obstruction in the hole or if the hole is fully milled out. Was there anyway you could of been actuating the lever? Did someone else fire the rifle and replicate the issue?

I did not pull it off, but did note that it felt that it was fully engaging the hole as in the other positions. Someone else was shooting it as well and exprienced the same same issue. I"ll pull it off and if there is anything going on with the buffer tube..