On the 4 shot i noticed my gun kick me more than usual
Classic signs of an overloaded shell. Probably a double charge if I had to guess.i found the shot shell had blown out from the bottom and it broke off a fin on the rotating bolt. The barrel at the chamber also has a small tiny bulge.
I'm surprised a load this light will even operate a Benelli (5500 PSI, 1125FPS)i used a remington gun club hull with 17.3 gains of hodgon clays, win 209 primers, 1 oz of shot
and windjammer wads.
I assume you mean grains, since .3 grams would be 4.6 grains.im always within +- .3 grams of powder