RCBS Neck Expander undersized

[41 mag fan]

Has anyone had an RCBS neck expander be undersized? I have my 300AAC blk out dies, formed all my brass, and after many moons now, have finally gotten time to start loading.
My casts are dropping at .310. First one I tried as a dummy round shaved lead.
Checked my casts, no growth, checked the expander and it measures by calipers .306, by micrometer .3055.
Tried a 30 caliber j-word, and it was oversized even.
Anyone though ever encountered trouble like this?

Calling RCBS as I write this to see what they say and hopefully get the right expander sent to me.

As an update, just got off phone with RCBS guy, he told me the expander should be a nominal of .307, and that mine is undersized. Talked a few minutes with him, turns out he's a hoosier from his youth, but he's putting in a note for the whoever, to measure me one out thats larger than the nominal. Thought that was really nice of them.

As an after thought, I've watched what seems to me to be RCBS taking a downturn on quality over the last decade, esp the last 5 years. But it's hard to beat the no questions asked policy they and Hornady have.

[462]

Expander dies are designed for jacketed bullets, and .306" would give .002" neck tension on a .308" bullet. However, your .3055" is, definitely, too small.

For a .310" boolit, my preference would be a .308" expander.

[BK7saum]

Even the 30 caliber lyman m die is ~.306, maybe .3055, if I remember correctly. I ended up purchasing the lyman 31 expander which measures about .309 or .3095 for my 300 whisper.

It has been my experience that most dies are set up for jacketed bullets and we have to modify or tinker with the system to get things to work out right for real boolits.

[41 mag fan]

Even the 30 caliber lyman m die is ~.306, maybe .3055, if I remember correctly. I ended up purchasing the lyman 31 expander which measures about .309 or .3095 for my 300 whisper.

It has been my experience that most dies are set up for jacketed bullets and we have to modify or tinker with the system to get things to work out right for real boolits.

I might have to look into the Lyman dies and see if that'll do the trick

[BK7saum]

Your only other option is a custom expander by Buckshot or some of the other fine folks on this site.

The 31 Lyman expander gives satisfactory neck tension in a 300 blackout with .309 gas checked NOE 247 boolits. With a .310 boolit, it should be perfect.

[41 mag fan]

Thanks BK, I'll check into it and come up with something.

[cbrick]

While the small diameter sizing plug may size down the boolit diameter in the NK the shaving you mentioned is probably due to a lack of belling the case mouth. Look into Lyman M dies.

Rick

[Smokin7mm]

RCBS also make expander (belling) dies for all calibers for use with cast bullets to avoid shaving lead.

Bret

[41 mag fan]

Couldn't find a lyman die in stock anywhere, but i found a RCBS .311 in stock at Natchez. I bought it and now have to wait for their sloooowwww shipping.