xausa:

The note of a 0.25 Remington is a good point and it had slipped my mind. But I was mistaken on the little Husky squirrel gun and it is a 0.25-20 Winchester. Then the 6.5x41 is the 0.25-20(J. Francis Rabbeth)Single Shot and their dimensions aren't anywhere close. There isn't a "R" on the chamber, but a chamber cast revealed the mystery cartridge and that's why it should be the first step in eliminating many of the cartridge possibilities.

Kind Regards,

Raimey
rse