SGT Horvath should have been 37 at the time of his death roughly the actors age. That would mean he was born around 1907. Sizemore also has a "Detroit" mid western accent, some of the ways he says things and expressions are very regional to Michigan , Ohio, and Indiana.
Pistol[]
The pistol he carries is a Colt M1911A1 model. It does fire a .45acp round but the designation is M1911A!.