[SSN Vet]

I want to upen up a Lee sizing die .001" to .002"

I have 200 grit machinist valve lapping compound. Is this to coarse?

I also want to "Leement" a two up mold.

I hear people talking about using toothepast.....

would my lapping compoud work?

[fecmech]

"Beagling" does not involve lapping the mould cavities. You simply put some aluminum tape between the mould halves to hold the blocks slightly apart which gives you a slightly larger bullet. You may think that the bullet being out of round is detrimental to accuracy but it is not. The bullet is still in balance and they shoot well. I have a Ruger Super Blackhawk .44 mag which has .434 cyl throats which cause serious leading with light loads due to gas blow by. I "Beagle" the bullets for that gun and size to .433 which totally eliminates the leading with light loads and improved the mag load accuracy. The gun off the bench will average 2-2.5" groups at 50 yds with both light and 1400 fps mag loads with cast bullets.

[mkl]

I would think 200 grit is pretty coarse for what you want. The inside of the sizing die must be pretty well polished to prevent cases from sticking. I doubt you could get a polished finish with 200.

I've use 320 grit on a collet for a bullet puller and it worked well, but the inside of a collet probably does not need to be as smooth as the inside of a sizing die.

More knowledgeable people than I are on here regarding lapping, but I'd make a first guess at something like 320 to open up and 600 to 800 (maybe even finer) grit to polish finish after you have the correct size. I use white rouge buffing compound sticks to polish carbon steel on my buffing wheels; perhaps it would work well inside of a die.

Just reread your post. If your are talking about a sizing die for lead bullets, forget most of the above. When I read "sizing die" I thought of cartridge cases, since I don't cast my own bullets. Sorry 'bout that.

[snuffy]

SSN, are you talking about a lee push-through boolit sizer? If so, they your 200 grit is way too course for that. You need some 400 for the initial cut, followed by 600 to finish. Otherwise, you would end up with very rough surfaces on the boolit.

Ditto on the lee-menting. It is something I never have tried, the al. tape thing. I did the abrasive paste on a boolit cast by that mold, then spun in the cavity to get rid of burrs, and increase diameter a tiny amount. Again though your 200 grit is much to course for that as well. I used flitz on mine it worked well. An abrasive like comet sink cleaner would work too.

[rcmodel]

I think 400 Emory Cloth wrapped around a slotted dowel in a drill might be the best way to open up a lee bullet sizing die.

Unless you have a lathe & an adjustable reamer.

200 grit valve grinding compound is great for valves, but not much else.
It's way to coarse for lapping.

rcmodel

[Griz44]

I used comet on my Lee aluminum mold and Lee sizing die to open it up just a tad. Drilled a hole in a bullet made in that mold and put a long screw in it for a handle. Five or six revs did the trick. Then I pushed a comet coated bullet through the die 4 or five times. Bullets just fall out of the mold now and sized bullets fit my very slightly oversized colt barrel just right! I only use that mold for that one gun, as my newer guns fit the factory molds just fine.

[GP100man]

i`m with Grizz44, comet is not too aggressive & easy to clean off.
i even use it as a slurry to derust a boo boo on steel molds, makes em nice `n smooth.

GP100man

[SSN Vet]

thanks for the replies...

sorry if my terminology was off.

I am trying to open up a Lee push through bullet sizing die from .311 to .313.

The mold is dropping bullets at .312.

My intent w/ the mold, is to smooth it out to improve bullet drop and remove some machining imperfections that are showing up on the bullets.

If the mold opens up to .313 in the process, I should be just about perfect, as the rifle slugs .312 at the muzzle and is showing some leading there when I size the bullets to .311

I think I'd be fine shooting the bullets as dropped, but need to seat the checks without losing diameter on the bullet.

So I'll shelve the 200 grit lapping compound and give the commet and some 400 git emery cloth a whirl.

a sound approach?

[GP100man]

sounds like a flapp wheel time to me, i`d get some fine stuff to do the finishing polish on that push thru maybe even some #7 car polish.

GP100man

[SSN Vet]

sounds like a flapp wheel time to me

that would be my preference, but where can I find one small enough to do a .311" hole?