pre war and early war followers

[RCS]

the revision 8 (middle stamp) started in 1941 soon followed by the end marked 8

the revision 9 has been found in the 500K serial number range

[Orlando]

I was going through some parts the other day and found a couple of the revision 8's stamped in the middle.I never have found a 9 yet

[RCS]

Tony Pucci reported finding a revision 9 in a Lend lease s/n 533252 rifle back in 2010, Charles Redfield also found one too. There are
suppose to be some revision 10 followers but have yet to surface.

[Jersey Devil]

I have two center-stamped "8" followers, but no "9" or "10" examples.

What's the popular thought on the "8" follower with the "cup marks"?