With a reaction rod or anything that immobilizes the barrel extention while applying force to the barrel nut runs the risk of shearing the barrel index pin off. Doesn't happen often, but will mostly happen with an extra tight barrel nut on removal (not so much during tightening).
The Grendel/762x39 bolt exterior dimensions match the 223, so your reaction rod will probably work. But if you haven't purchased one yet, consider one with a "sail" that bears against the receiver in addition to the extention or a Bev-Block which bears against the mag well in addition to the barrel extension. Or look at the White Oak Barreling rod which doesn't bear against the barrel extension at all. The idea is that you don't want the receiver rotating with the nut while you're applying torque to the barrel nut against an immobilized barrel index pin.
Last edited by ChrisF; 03/17/24.
