CTG stands for cartridge, according to the answer given in this forum: http://www.e-gunparts.com/forum/readit.asp?qt=56666&cat=14
'ctg' cartridge
Cartridge
Cartridge
Cartridge
Email smith and Wesson for the answer
Yes
S&w
Cartridge
Smith&Wesson model 14
1982
Springfield, MA
1977.