(this could easily go in the gunsmithing forum, but it's about an often discussed topic for Mini- rifles, so I put it here)
I'm going to go all Billy Mays and give you a sales pitch here, but it's because I just used a product I found on the web and it is EVERYTHING the maker promised!
I want to shorten the barrel on my Mini-14 because they are known to whip and reduce accuracy because they are so "pencil thin". I don't know how short, because I want to test the effects of cutting it down incrementally. I just need sense enough to stop when I see an improvment.
Knowing I would probably need to cut and recrown two or three times, I couldn't justify the expense of a gunsmith, several times over. Enter the World Wide Web... I found a video of a fellow demonstrating a tool designed just for my sort of needs that would allow me to do a simple recrown at home with a minimum of tools.
I cut my barrel with an ordinary hack-saw in about 3 minutes. It's adviseable to put it in a vise with a protective cardboard wrap so that you can cut it nice and straight. Clean it up with a file if you have that barb sticking out at the end of the cut.
Then follow the instructions included in the package (the video is a big help here). It takes several cuts with the crowning tool, clearing away cuttings and adding cutting oil occaisionally. Don't rush it and let the tool do the work. You'll be done in 10 minutes. Remember to lap the muzzle lands with a brass lapping ball and a little lapping compound. You can get these from Midway or use a round head brass screw and a dab of rubbing compound like I did. Finish by breaking the outside edge with a fine tooth file, and apply a little cold blue unless you have a stainless barrel.
Easy, professional results that are repeatable for about $125 using your own cordless screwdriver. If you need one barrel crowned, you might see your gunsmith. If you need several, call Dave at Manson Precision Reamers!
What you see here is the pilot, cutter head, drive adapter and drive bit that come in the kit. You can specify 11* or 0* crown. If you have a larger barrel, they have chamfer cutters to finish the outside edge nicely. For the price of the kit, you choose one caliber, .22-.27 in my case. If you want another caliber pilot, it's a modest additional cost. I need to order one for 7.62mm for my Mosin Nagant.
Here's Dave to show you how it's done: