If you want to see performance on those dry magazines, try alloyed lead round balls. WW metal is my preferred as it's so cheap- normally free, casts well and still maintains good weight for diameter. I smashed both shoulders of a big Canadian bull moose with one from my 14 bore rifle -.684" round ball weighing 466gr. Moose was 100 yards from the muzzle. Lyman and Lee both make RB moulds in .690". The Lee mold is a cheap way to test balls - at less than $20.00US normally. Jeff Tanner of the UK will make any size desired, up to and including 8 bore, for around $30.00US.
; You can contact me if desiring more info on this type of loading for a shotgun.