What does this mean?

[Trophyhunter49]

  BigErn you ain't rite 

[1377x]

2 screw grip frame. Gun looks to be made March 2010. I think eventually I'm gonna sand that "R" off of there.. I don't like it.

kinda figured but had to ask. the 2 screw is the only one I have seen the "R" on.

[twigboy]

kinda figured but had to ask. the 2 screw is the only one I have seen the "R" on.

Mine is three screw with the "R".  Reman'd PC77.  Not that it would matter but the serial shows it was made November 2012, while my other non-"R" PC77 was made March 2011.