Opening a sizer

[Lead melter]

Does anyone have a surefire, idiot-proof, easy method of opening a Lee sizer die without the aid of a machinist?
The die in mind is a Lee .410" that I would like to open to .412" in preperation of a couple of molds for Group Buys. Boolits are scheduled to be about .413", my Blackhawk has .411-.412" cylinder mouths, so I probably need a little larger boolit.
Any info will be helpful. If there is a sticky on it, just point me in the right direction.
Muchas Gracias.

[RayinNH]

Lead melter, go to http://www.castpics.net/index2.htm

Research and Data:Honing a size die (by Buckshot)

...Ray

[dubber123]

Saw a cut in the end of a wooden dowel, wrap with some 320 or finer grit sandpaper until it is a snug fit in the die, spin it with an electric drill moving the dowel/sandpaper in and out. Hone evenly to prevent tapering the die.

If the die is really hard, and you aren't making any progress, heat the die until a dull red, and let it air cool. This will soften it. I have only had to heat one die so far.

In case you have a very soft die, it is best to measure frequently when you first start to get the feel of how quick it is cutting. You will most likely have to replace the paper several times. If you have some 600 grit or finer paper, it is best to use this to take out the last bit, to give the die a better internal finish.

[skullmount]

What will you use to slug the die as you lap it? to check for size

Go slow....real slow!

[454PB]

I've done Lee sizer dies and they are quite soft.

I use a lead slug and push it through to check size using the tailstock on my lathe. Without a lathe, just lube lightly and shove the slug through as you would any other boolit. The same slug can be reused as you proceed, just put it in a vise and squeeze it to re-expand for the next test.

[Lead melter]

Thanks for the tips, guys. I'll give it a shot at work tonight, using the drill press set on its lowest speed, about 400 rpm. I especially like the vise to swell the boolit bit. That'll save some lead and gas checks.

[454PB]

Why would you shove a gas check through when all you are doing is getting a measurement?

[Lead melter]

Why would you shove a gas check through when all you are doing is getting a measurement?


454PB,
In preparation of the opening of the .410", I am opening a Lee .429" to get some experience. The .429 is one I don't use and am trying to open it to .431". If I mess this one up, it's no great loss. I'm using previously cast and checked .432" boolits for the trial, so the check goes also.
Good question.