Having trouble with Lyman size dies today

[NuJudge]

After carefully measuring sized bullets with several calipers, and checking against bullets of known diameter, a .429" size die is putting out .428" bullets. I could forgive it being large, but not small.

This is a die I got from a relative. Is anybody still reaming these out? If not, how do I do it myself?

CDD

[GabbyM]

Impregnate two bullets with compound by rolling them between two steel plates. Or whatever flat junk is handy.

Disassemble the sizer arm that returns the punch to make the sizer into a straight through unit. Then push the slugs through out the bottom like you were using a Star. Catch the one coming out the bottom and run it back through. Spring back of the lead will keep things tight. About twenty strokes later you should clean up for measurement by running a fresh unsized bullet through. I've taken a half thousandths out with forty passes using 220 grit compound then not had enough metal left to clean up to a smooth finish with fine 600 grit before going oversize. That was on a heat treated Star die. Use a little oil to keep things moving along.

When you're done you'll have a loose fitting pin that may leak lube out.

[DLCTEX]

Search out buckshot's advice on enlarging a die. I beleive it was a Lee being opened up, but the process is the same. Split dowel with fine sandpaper and roll the die on your pantleg, is a simplified version of it. DALE

[beagle]

Good advice. Have buckshot open it up.

You've discovered a lesson that few casters ever learn. Measure the sized bullet. Few sizer dies will turn out what is stamped on them.

I took my dies, sized bullets and measured the output to 4 places. I remarked in some cases. I store in film cannisters with the actual measured diameter on the lid. Works pretty well./beagle

[ra_balke]

Gezz, don't bite my head off for this you guys ...ok?

Get you a wood dowell, about the right size, and cut a split down the side.
Incert a piece of fine grit sandpaper in the slit, and slide it down the inside of the die.
Spin it around a few times, round andf round, and up and down, then test the die for size.

If it is right, stop, if it is not big enough, spin it a few more times, and try again.

Normally, a .430 or .431 bullet works better than a .429.
Keep yur bullets a little over size..

[runfiverun]

balke you got it about right.
about the only ones who's sizers are the size you want/order are magma's, and at 40.00
each they better be.

[EDK]

If your machine is a LYMAN; when you ream the old die very much, it will leak lube out the bottom! Order a new one (in .430 or .431) from Midway or Grafs or Buckshot or ? and save yourself from aggravation.

If it's a STAR, I'd lap it....or watch for a used die on auctions/classifieds.
Refer to other threads about boolits "growing" with age...are yours freshly cast?

:Fire::cbpour::redneck:

[GabbyM]

Well fellows You'll get a bore with less tapper using lapping slugs as I suggested in post #2. Over a hone of any design. I've used a hone to polish bores. The in house made ones from split dowels are great for polishing up scratched up dies. But the O.P. wants to remove .001". Not saying you can't do it with a flapper hone. Just that it's not the easiest and surely not the best way. Even with a quality dedicated hone machine using rigid stones it takes a skilled operator to hone a bore without a tapper. Your dies will wear in a tapper open at top closing at bottom with use. If you hone a revers tapper you'll get a surprise down the road when the top diameter wears off your bore. Once again I'm not saying you can't hone out a size die and achieve good results. Just not my idea of the best or easiest way to do it.
As an example seen in our sport. Bench rest barrels are lapped using abrasive impregnated lead slugs pushed through the bore with a broach machine. Or by hand tools in small shops. The lead end of the bore will be the chamber end since it will have an oversize dimension due to starting the slugs to compression. After the first couple of inches the bore deviation is measured in microns. Fellows that's way better than we need in these size dies. BTW I've been a machinist for thirty years. Unfortunately. Not unfortunately the machinist part. Just the thirty years of anything. Hundreds of hours of which were spent honing parts with .0002”' tolerance.

WOW ,,, I had to bend my neck back to read all that. Guess I lived up to my handle.

Suppose now the question is. Do you have lapping compound or a dowel stick and emery paper.

Ditto what EDK just said and I said in post #2. You may have a leak anyway.
I've about 15 RCBS dies here and every one is dead on size. That's why they cost more.