Mosin Nagant rifling/bore rust/back bored.

[Mauserbill]

Hello
I have a number of 91/30s all with very good bores, rifling and muzzle crowns.
I have always been intrigued on the effects of the above on accuracy, I recently watched a YouTube video where this person took a Mosina with a rusted/pitted bore, cleaned it and then shot really good groups. Also I have heard and know what back bored Mosina barrels are but have always dismissed them as seconds. I was recently offered a Polish M44 in excellent condition and would have purchased it on the spot until a checked the muzzle and found it had been back bored, looked like the person had done it with a electric drill and a 8/8.5mm drill bit. Many of the Mosina`s on the market are advertised with bores that are either back bored, pitted or frosted, and show very little if any price difference between them. I suppose bad arsenal storage and the lack of cleaning after using corrosive primers has taken its toll.
Has anyone got first hand experience of shooting a Mosina in both 91/30 and M44 with this type of bore condition and its comparison to rifles with cleaner better bores.

[snayperskaya]

I had a 1939 Izhevsk 91/30 that had it's original crown but a frosty bore and worn rifling in the top couple of inches to the muzzle but it would still shoot 3-4" groups at 100m with milsurp ammo.My '26 Izhevsk ex-Dragoon is counter-bored (back bored?) around 1.5" and that shoots really well, especially with hand loads.

Many Mosins were counter-bored when they were Arsenal refurbed as it was an easy way to get back to decent rifling if the muzzle was worn/damaged, rather than cutting the barrel down.

[Blighty]

Most of the Finn capture 91/30 rifles that I have ever come across/owned have been counter bored. Never thought twice about buying them. If a nation during desperate fighting took the time to shim the actions, tune the triggers and counter bore the barrels of captured rifles then it could only ever be a good thing.