I have an m91 with a "D" marked barrel and the inside is deplorable, but it can actually shoot pretty well since working the crown. I crowned mine at 14° with the intentions of working back a degree to 10° to see if crown angle actually effects accurucy and if so, if less is better for flat-base and a little is better for boat-tailed, as I have seen rumored on the web's. Anyhow, I had major improvement right off the bat with the 14 and have since all but forgotten how much of a pain it would be to target crown a mosin 5x. Any crown, whether a flat or 11° is going to make your mosin shoots like a totally different gun, as long as you take care to be concentric. I've been shocked at how bad the barrels can look visually on some decent shooting mosin's, and if your having accuracy issues and you have made sure your stock is movement free, bedding may be absolutely nessecary or maybe just an extra step to ensure more consistency, and your rifle is floated with 're-enforcement to the recoil lug.....I would hit that crown and I'd bet money, well....like uh, five bucks or something, that the crown may be the biggest accuracy benefit and can be done so in a way that will not tarnish the collectibility to the extend that wooding out stocks and floating does.
As the days pass and I see the Mosin market run dry and pricey, I do think I'll ultimately regret shortening the barrels of my m91 and should have used my old Russian 30, but at the time with no original Finnish stock and zero availability when attempting to track one down, I figured it's not going to make a stink, but I shoulda tried harder or just waited and took advantage of the $125, seemingly bottomless, 91/30 market for my project.
It was a hard decision for me to make between the late date and the B barrel. But in the end I just went for the Late Date since I already have a war time M39.
