Mark, the top rifle is the .22 M2, which undoubtedly has a correct 48C.

The middle rifle has a very early 48, the long-slide option, which is NOT correct for the Style NRA rifle (the "Springfield Sporter").

The bottom rifle looks correct except with a substituted cocking piece. The sight looks to be a proper Lyman 48. If it is, it will have a "turn-down peep", which can be turned up to give a smaller peep if wanted when hunting with the aperture disk properly removed.