Skeeterbd;
I believe this 3 ton proof is about an equivalent of 10,640 PSI (This may not be exact but close) & as such is not the eqivalent of either modern day Superior proof or SAAMI specs for 3" guns.
There has always been some question in my mind on the LC mark. The proof rules for at least some of the years read the LC mark was to be applied to guns with chambers "Longer" than 3". However it seems that 3" chambers are found with both the standard C mark & the LC mark, so apparently some of the proofers were somewhat confused as well.
