Geissele

Up until about a year ago, I exclusively used a Derlin action block much like the one seen here. Derlin blocks are useful but introduce other issues such as setup time, lining up pins, torque flex, etc. I often found the need to apply more than mil-spec torque to the barrel nut when installing a barrel and could visually see the upper flexing. It made be cringe but I didn’t know of any other option.