Neat huh?
FPJ bolt and Bare 209 plug. The SS FPJ is machined to fit the SS breach plug. IIRC he uses the new tungsten bushings being made on Dougs for the smokeless crowd. Then modifies the Knight plug to accept them.
IIRC he said the huge loads of BH209 were eating up vents in under 30 shots. These bushings last a long long time.