RCBS Expander Size Question

[Four-Sixty]

I bought a used set of 30-30 RCBS dies. I noticed after trying to seat my boolits, that there was a heavy amount of lead shavings. I unscrewed the rod with the expander on it and measured it. I got a size of .306 for the expander. Is this correct? I know this set of dies belonged to a guy who was into machining. I was wondering if the expander should measure around .309, and if maybe the prior owner of these dies reduced the diameter of the expander to get a tighter fit.

My cast boolits are sized to .310 and I have to balance them on the case mouth before I run them into the die for seating. I can't even get my boolits to start into the case mouth.

What should the expander measure?

[BCB]

The expander in my 30-30 sizing die is 0.3085"...

You will need to get an expander die for cast boolits...

It expands to whatever diameter you purchase it for and puts a flare on the case mouth to assist in boolit alignment and will prevent the lead shaving...

RCBS makes them as does Lyman--I use RCBS and I think Lyman are called "M" dies...

Good-luck...BCB

[Four-Sixty]

Thank you Sir! I was hoping that a .309 expander would be, well... .309". Mine must have been modified.

[GabbyM]

RCBS Cowboy die sets come with a separate expander die very similar to a Lyman M die.
You can buy the RCBS Cowboy expander separate if you can find it.

[462]

Reloading dies are dimensioned for jacketed bullets, not cast boolits, and your .306" plug is correct for a .308" jacketed bullet. RCBS makes individual expander plugs that are dimensioned for rifle cast boolits -- check their web-site or give them a call.

[BCB]

Reloading dies are dimensioned for jacketed bullets, not cast boolits, and your .306" plug is correct for a .308" jacketed bullet. RCBS makes individual expander plugs that are dimensioned for rifle cast boolits -- check their web-site or give them a call.

I’m not so sure that is correct—the 0.306” part…

I measured several 30 Caliber dies that I have and I got the following dimensions:

Hornady 300 Winchester Magnum 0.3075”
Lyman 308 Winchester 0.3075”
RCBS 30-06 Springfield 0.3075”

All the same +or- 0.0001”

The Hornady jacketed bullets I measured were all right at 0.3085"...

Measured with a Starrett micrometer…

BCB

[462]

I mic'd three RCBS .30 caliber expander plugs (the brand Four-Sixty is using). Two measured right at .306" and the other at .3064". Other brands have different dimensions, however all are too small for .310" cast boolit use.

[BCB]

Whatever on the size of the expanding plug in a 30-caliber sizing die…

But I use a .309” or .310” expander plug, depending on what boolit I am reloading, with the RCBS expanding die…
(I also measured these and they read what they are to be with the Starrett micrometers)

I just purchase the one die and then purchase expanding rods and put the size of expanding plug I will use on it. I then just change expander rod with the correct size plug from the die and that way I don’t have to have several dies—just rods and expander plugs for each diameter of boolit I use…

Good-luck…BCB