These have become my favorite rifles. Here's a brief run-down of my two cents on various makes:
Original 1891--These are long, heavy and fun to shoot. But they have the same goofy tangent sights starting at "400" (400 Russian somethings, IIRC), that most 1890's era rifles have.
Russian 91/30--The classic WII M-N. Long, but surprisingly light and well-balanced. Accuracy and quality mixed. I've had my best luck with pre-war production. But even the good shooters get only about 2MOA. Some are much worse, a few sniper models are better. It's a workhorse rifle. The tangent sights start at one hundred meters. Parts are cheap and easy to obtain as are sporter stocks, scope mounts, mojo sights, etc.
Russian M38 Carbine--This is my favorite carbine. Sadly most of the stuff on the market has been abused and counter-bored to stretch the barrels beyond their normal working life. Accuracy can be horrible. Get one that hasn't been counter-bored and slug the bore to make sure it's not nearing the 8mm mark!
Russian M41 Carbine--These are the carbines with the built-in bayonets. There are a lot of unissued Polish ones out there that shoot OK, but IMHO they are too heavy.
Finnish Captures--Anything with [SA] on it was most likely captured by the Finns during the Winter War or Continuation War. Some of their captures are unaltered, some improved a little and some improved a lot.
Finnish Mosins--The Finns used old 1891 receivers to build custom Mosins for their small military forces. The varieties are too diverse to discuss here. Generally the most beat-up are the M-28's and variants that saw the rough end of the Winter War. The M-38s from the less intense Continuation War are often in excellent condition, and have the reputaiton for being the best shooters of all Mosins. All Finn Mosins tend to be heavier than Ruskies, mostly because of thicker stocks and heavier barrels. If you want a rifle which most likely saw active combat, get an old M-28 "White Death" rifle. The Winter War was without doubt one of the most intense conflicts of the 20th century.
As far as ammo, the Berdan primed modern Ruskie production is at worst very mildly corrosive. I've never had a problem with it. Surplus ball can be very corrosive. The Boxer primed S&B should not be corrosive at all. The modern Ruskie ammo is quite good, BTW. Don't let the low price fool you.
