How do you open up a sizing die?

[igolfat8]

I have a Lee .401" sizing die. How does one open it up to a .402"?

[zuke]

I like to use a 30 cal patch holder and 400 grit paper in a drill press

[igolfat8]

Is the die hardened steel or carbide?

[slide]

I used a dremel with one of the little sanding drums. The key to success is go very slow and check often. You are going to need some bullets to check your progress. I went ten revolutions and checked. You could probably do it by hand.

[Beagle333]

Spin a dowel rod with emery cloth or sandpaper. I add or remove some paper towel wrapped around the rod under the sandpaper to change the thickness as I go. Go slow and finish the last little bit with some 600 or 800 grit. It's pretty easy to do. Check size often during the process. Be very careful if you use a drill when going only .001 in size. That'll almost be what you would get if you just polished the heck out of it with the 800 grit. Personally, I'd go with hand turning on something that close.

[DougGuy]

Use a wooden dowel, 3/8" and cut a slot in the dowel 1" long. Put a 1" wide strip of 400grit paper in the slot and wind it around the dowel. Try it for fit in the die, if it won't go cut off some of it. It will eventually go into the die and just spin it with a hand held drill or put the dowel in a drill press. It won't take much! You could polish it with 600grit if you want to.

You almost need a .402" pin gage to proof your work. McMaster Carr sells individual gages, I would get a Z class minus gage which will be .0002" under .402"

[EDG]

If the die is steel buy a barrel lap that will open to .401 and use it with abrasive paste lapping compound. Use about 800 grit.