Does anybody know if anybody besides KAC makes a thinner than normal castle nut? I have a knights qd endplate and refuse to use the impossible to tighten/untighten nut kac includes with it.
You can use the regular castle nut, it just won’t let you completely collapse the stock 
The one supplied by KAC with the QD receiver sling adapter is the old kind of slip ring, you can still buy the el cheapo wrench for it, some armorer’s tool still has it.
disregard!
You’re at the wrong end of the gun. OP was asking about the receiver extension nut (aka “castle nut”). Also, if his barrel nut was somehow interfering with a rail’s QD socket, why would he want “the thicker awesome core 15 barrel nut”?
alright!calm down!i thought he was referring to a barrel nut.