size of unmarked rifle

Discussion in 'General Rifle Discussion' started by murraywc, May 17, 2010.

  1. murraywc

    murraywc New Member

    I found several rifle barrels with recievers and bolts in a rental house we owned one was a 03-A3 one was a G33/40 one is a rather large barrel with no markings the bore is .253 and the chamber appears to be a 25-06 what is the best way to find the size. One of our local outdoor centers suggested either take it to a gunsmith or just try a 25-06 shell in it, if it will chamber that is it because it is the largest of the 25 cal shells. Any suggestion.
  2. Dr. Marneaus

    Dr. Marneaus New Member

    Take it to a gunsmith or do a cast of the chamber and have it measured.

  3. murraywc

    murraywc New Member

    what should I do the cast with? and what about the 06 being the largest of the shells?
  4. robocop10mm

    robocop10mm Lifetime Supporting Member Lifetime Supporter

    The G-33/40 is a small ring Mauser action originally intended for the 7 X 57 class of cartridges. It may have been rebarrelled to .25-06, but IMHO this is not a truly "safe" conversion as the .25-06 has higher operating pressures than the 7 X 57.

    Have a gunsmith make a chamber casting with Cerrosafe to get the answer.
    Last edited: May 18, 2010
  5. c3shooter

    c3shooter Administrator Staff Member

    As Robo said. Cerrosafe is a low melt temp material with unusual properties. After it cools it shrinks- so that it may be removed- and then- miracle of miracles- returns to it original size, so you can use a micrometer to accurately measure it.

    Although in a pinch I HAVE plugged the bore, pounded lightweight aluminum foil into the chamber, pushed it out and measured it. But Cerrosafe does much better.