From my observations it seems that those X and higher "features" of rebates, profiled breech balls and the lock-screw on the tang-screw seem to be very hit or miss.
I can remember collectors who only wanted XE-Grades like this --
29320 07 Watertable.JPG
that had all three of the "features."
Craig, I can't tell from your pics if your guns have the profiled breech balls. XE-Grades 22458 and 22578 are "head down" that have profiled breech balls but no rebates or lock screw --
22578 05.jpg
XE-Grade 22088 doesnot have profiled breech balls --
22088 04.jpg
Hybrid Mode