Had it been 8" RPM and a thunk given at throat geometry,it woulda connected all dots. Hint.
The Forbes S/A magbox's are relatively roomy in COAL,while their L/A is not. A 280 quickly runs itself outta room there,just as a Montucky or Fieldcraft does as well. Too bad all. Hint.
Hopefully,as a minimum the barrel is S/S.
Hint..................
