'FULL TALONS' can be defined as full separation of the three talons on each foot of the eagle on the reverse of the Susan B Anthony dollar coin.  This separation may not be violated by a hit or by a bridge.  It need be apparent at only one angle of view, however.

For a complete accounting of this strike attribute, please see my cover article in the May 2006 issue of NUMISMATIST, available on line at the ANA website,  money.org   (DR Golan was co-author).

In brief, Full Talons (FT for short) occurs in as high as 75% in 1979-P SBAs and as low as 10% in 1980-S SBAs.

It does not seem to be a function of die wear or coin grade. 

The most likely cause, in my opinion, is grease (used to lubricate the dies) collecting in the talon-olive branch unit of the reverse die, preventing planchet metal from flowing into these recesses. 

FT is not recognized, yet, by any Third Party Graders, but all are interested.  TPGs (like PCGS) follow numismatic trends rather than leading them.   TPGs will wait for their more important SBA customers to demand attribution of Full Talons before committing to the expense of tooling up to create their own definitions of FT and making provision to add this attribution to their holders and population reports.