There are no caliber markings that I can find.The serial number is 305 found on the butt and on the barrel under the ejection rod.
Thanks for all your help.
1x1time
I'll do the best I can giving info on this gun.
Swing out cylinder
No mod. number
5and5/8 barrel
four screws on right side of frame
no screw in front of trigger guard
screw on tang
three didgit serial number
black plastic grips
Thanks,
1x1time
***In addition, I'm pretty sure it is a .38...