I just bought an AyA 4/53 in 20 gauge, circa 2009. While it is marked imp cyl/mod when using my trusty rusty Galazan choke gauge I get blunderbuss and cyl? I don't have the ability to mic the barrels behind the choke to figure constriction. Is it safe to assume this is a bore size issue? I can't see any indication the chokes were modified in any way.
Thanks,
CHAZ