Mosin Barrel
I went DIY and machined it off on an old lathe. Was pretty easy but then you need access to a lathe. Maybe find a machine shop near you that wouldn't mind doing it. I decent machinist will have the tools and know how. I only suggest this on an inexpensive gun that you didn't pay a lot of money for all the obvious reasons. There are people out there with the best tools for the job but paying more for the barrel to be machined than the gun is worth sounds kind of silly.
(there's a ton of dust and fuzzies the camera flash picked up when shooting the picture that look like burs but they aren't. Burs on the inside of the muzzle will mess up your bullet trajectory and having to sanding them or trim them away means the muzzle will have more imperfections on it rather than just getting a smooth cut with the lathe. Although, microscopically it will never be perfect.)
Gander Mountain, Cabellas and whoever else might not be nearly as good at machining steel as you would like to think even if they are a gunsmith. Someone who builds tools and uses a lathe all day can get that barrel re-crowned and perfectly straight almost as fast as you can take it apart, they just need to know what you want them to do. I'd bring a picture or what you want and/or make sure they understand what they are doing you know......
1. faced-off perfectly square and/or beveled/tapered in toward the inside of the barrel or whatever you like.
2. NO burs on the inside of the barrel straight off the lathe. You start from the inside of the barrel with the bit tilted a tiny bit towards the outside to allow it to shear the metal without pushing a bur towards the inside of the barrel. This will give a smooth clean cut. Meaning if they can't face of the end without having to remove burs from the inside of the cut/barrel they are doing something wrong. The outside doesn't matter as much but even then it's so easy any burrs and I would force redo, not to mention it takes less than a minute to actually do.
3. You can always cut more off the end of the barrel but you can't put more back on. So if you're unsure have them practice an inch up to find out before making the money cut. Also make sure you're not making your gun illegal by making it too short.
And remember, don't hack the barrel off with a grinder or saw you'll never get it straight as a lathe. And sanding it smooth or sanding to remove burs afterwords will never be as straight as a good lathe cut. I made sure I had a sharp bit and just turned the knobs although I have some experience with a lathe and none with crowning a gun barrel but mine came out excellent and shoots much more accurate then when it was in original form. But again, really only want to do it on a mosin or other cheaper/surplus gun. My more expensive guns have never needed re-crowning but if they did, I'd have someone do it with the best tools possible instead of what I have access too.