Enlarging a sizing die?

[Sweeper]

So, here's the issue I have- I'm not in a position to buy a higher priced lubesizing system, so I'm using what I have- Lee sizing dies.

This is the issue, I need .312 and .313 sizing dies, but Lee only makes .311 and .314 dies.

So, is there a method I could use to hone these sizing dies out a couple thousandths? Or am I stuck with buying an entire upper end system?

[1Shirt]

Have opened a couple with emery cloth in a split wood dowl and twisted it by in the die until I opened it adequately. Some recommend doing same but by chucking the dowl in a slow speed drill. Test often.
1Shirt!

[Taylor]

Keep us up on this,as I intend to try it too.

[mroliver77]

I opened a Lee die by pushing boolits through imbedded with lapping compound. It went pretty fast.

[Oreo]

The best way I've heard is using the wet/dry sandpaper sold in auto stores. Get a few different grades of the fine stuff, say 800, 1000, and 2000. Get a wooden dowel thats small enough to fit loosely in the die with the sandpaper wrapped around it.

With the paper on the dowel, put the die on and roll the die on your thigh. Stop to check the size frequently, especially with the coarser grits. Remember to leave enough material for the next finest grit to polish off so that the end result has a good surface finish.

[MtGun44]

Split dowel, back 400 grit wet or dry with thin cardboard, wrap around and
spin in drill, keep it moving. Gage pins to measure are HIGHLY recommended,
otherwise drive a slightly lubed casting thru and mic it. Too slow to put into
the luber to test. Finish the final .0003 with 600 or 800 grit. You need to
be able to accurately measure to the .0001 for this work.

DO NOT do this with a caliper as your measuring device, only a .0001" mic
is good enough. If you don't have one, you may actually have the sizes
you want, and don't know. Calipers are +/-.001 at best. Enco tools online
has new Fowler brand mics for well under $50, lifetime investment.

Bill

[silverjay]

I used steel wool and buffing compound on an old cleaning brush. Chucked the brush in a drill press slowed way down. Went slow and measured often. Took about 20 minutes to open a lee up .001".

[wallenba]

I've used the dowel method, it works. I've also tried using a boolit with a drywall screw in the bottom covered in lapping compound, turned with a cordless drill. That works. Check often as you go, I use lead round balls for muzzleloadeing.

[Sweeper]

Thanks guys, I'll be giving this a try when my sizing dies come in.

[Oreo]

Direct measuring the dies with pins may help but different alloys will size differently in the same die so the final word is a test boolit pushed through and measured with a mic.

[375RUGER]

I do like MTGun44 describes.
I check the size as I go by passing a boolit through it.
I have opened them from .356 and .358 upto .369 and .376 respectively and they size perfectly round. plus a few that I only opened 1 or 2 thou.