a 12 gauge shell is going to barely catch on the rim of a 10 ga chamber
IF the firing pin is long enough to set it off - the explosion is going to slam that back into the breach face as it expands to fill the void left by the difference in diameter
so now a split and over stretched hull head is going to be jammed up between the extractor and breech face- i expect it will be difficult to open after that
firing just a primer will not prove any thing
please do not use a good gun-
IMHO - dangerous and foolish
i just hope this was a joke -
i have erased several comments about intelligence and seeing this on you tube
