Question on dies

[Toyoda]

A have 2 sets of RCBS 7 mag and 270 dies that have different numbers on the tops of the dies. I can't find what the difference is, need some help.
On the 7mag I have a FL/seat 70 and a FL/seat 73.
On the 270 I have a FL/seat 66 and a FL/seat 87. The 87 is a small base.

What does that mean?

[darkker]

Small base does almost exactly what the name says. So those dies resize your brass to a smaller base set of dimensions. So if company A normally sizes things a bit large, you may need a smaller set of specs to be able to resize certain brass that wad fired from a generous chamber. Most commonly at this point, it is vogue to use them in AR pattern rifles.

[Toyoda]

Can you point me to a list that tells me what the #'s mean? I searched but can't find (I'm sure its out there)

[bootsmcguire]

I asked this same basic question about the numbers on the top of the dies as I bought some dies that had different numbers and I am not an RCBS expert as I normally use Lee or Redding. The guys here told me that RCBS stamps the last 2 digits of the year it was made on the top of the die.

[BillPa]

A have 2 sets of RCBS 7 mag and 270 dies that have different numbers on the tops of the dies. I can't find what the difference is, need some help.
On the 7mag I have a FL/seat 70 and a FL/seat 73.
On the 270 I have a FL/seat 66 and a FL/seat 87. The 87 is a small base.

What does that mean?

The two digit number is the year of manufacture, "70" 1970, "73" 1973 etc.

Bill