Panzerschwein
member
The only stocks that were cut down to carbine length were for the M91/30s that were made into the M91/59 carbines.
It's easy to spot a M91/59 carbine. They have the longer rear sight as seen on the pic of the rifle Smithman 10 posted.
The stock on your rifle is most likely the original that was reworked or a replacement.
Counterbore Mosins were not done at random or just to correct the crown. When rifles were sent for refurbishment, they were done in large batches. The rifles were disassemble and separate it into parts. The barrels were inspected. Those that just needed to be recrowned were recrowned. A lot of rifles had bores that had damage to the first inch or two from improper cleaning. These are the rifles that were counterbored. It was much easier to counterbore a barrel then to cut it shorter and reinstall a front sight. Plus it kept the rifle at it's proper length.
I have Mosins that are counterbored that have bright shiny bores and shoot great..
Well we've got two different stories. I'll be the first to admit that I remember reading about this a long time ago, but cannot prove my side of the story and fully admit that it might wrong.
But can you prove yours?