I would get in the milsurp websites and look at what the reloaders say. I don't handload myself, but reloaders of these swag the bores for the very reason you describe. Some of the guns are very worn, others not so much. Most will be "dark" bores.
Many of these have wide tolerances, partly from wartime demands that made precise manufacturing too time consuming, battlefield wear and tear, etc.
Also, many of these were counterbored by the russian military arsenals, and that could perhaps affect the fit of your dowel. Literally, the last inch or so of the barrel was bored out at the muzzle because of a worn out crown. This was most common on the m38 and m44 carbine versions, though there are many 91/30s with it, too. The rifling effectively ends inside the barrel rather than at the muzzle. Shine a light down the barrel and you can easily tell if it was counterbored. The rifling won't come all the way to the muzzle, but will end somewhere short of it (probably an inch or two, though I've heard of 91/30s with up to 4 inches bored out). Counterboring was done for the same reason you'd recrown a barrel, so in theory it improves the shooting.
Last edited by Father Forkhorn; 06-06-2013 at 08:03 AM.