The M1908 Brazilian carbine with the 55 cm/21.5 inch barrel is one of the rarest of South American contract Mausers, especially since so many were converted to updated models. Even parkerized, it's an uncommon rifle. Is it matching? Can you post a picture or two?
I dug out Bell's book. Now it's looking like a cutdown rifle. The bolt is straight, and I didn't notice the barrel being short. I'm sure it was K98 like at about 24". I'm sure I would have noticed a shorter tube. To confirm that it's a 1908, that was on the right side of the reciever ring, a 4 digit SN and the circled "B" on the left.
Bolt doesn't match. Metal finish seemed more black than blue, and looked like it was on top of a fair bit of stippling (pitting?)on top of the barrel. It was on a table at the local flea market, so no photos.