The whole "ex sniper" Mosin thing is dicey at best.
See the Soviets would select high walled round receiver rifles that shot better than average right out of the factory and designate them "Sniper rifles". Do light mods on them such as lightening the trigger (
you can do a trigger job on yours to drastically reduce the pull and release with a clothespin spring, a pair of pliers and a small piece of an expired government card) tapping receivers/mounting scopes.
After this the rifles were
issued, used in the roughest conditions imagineable, shot who knows how many rounds through the bore of probably badly cleaned corrosive ammo. When a rifle would
no longer meet it's accuracy needs as a "sniper" rifle, it was converted or refurbed back to standard Mosin condition, probably went back out to the same war conditions and then was refurbed again and sold to the civilian market ending up in your hands for 2-3 times the price of a normal Mosin.
This usually what you are getting when you buy an "ex-sniper" Mosin Nagant. You pay more for a rifle that shoots just as well
now as the same Mosin in the crate next to it for $140.
So, you could pay god knows how much for a refurbished "ex Mosin Sniper" rifle that basically shoots and is in the same condition as any other run of the mill Mosin out there anyway, or you could buy a standard Mosin with a strong bore and accurize it yourself and save a lot of money.
Unless you could truly find a non converted, non issued, non "ex" Mosin sniper, I would say buy a standard 91/30 with a solid bore, do a few light accuracy mods on her, spend the other cash on ammo and shoot that f**ker all day long!
If you still insist on a true original condition 91/30 PU, then do research on them as they are easy to fake and when you're plunking down almost $1000 on a rifle that could just be a dressed up $130 dollar rifle lol You better know what you're looking for.
Check here, it tells you what to look for:
http://www.russian-mosin-nagant.com/sniper_9130.html