Roger, so far I recall seeing two original iron mounted guns done as you describe, with the toe of the buttplate hammered over the toeplate. One in particular was done very nicely, the toe end hammered very thin and filed to a rounded tip then neatly hammered over, covered the end of the toe plate by maybe a half inch.
More often I have seen the the toe end of the buttplate simply hammered over the toe of the stock rather than hammered onto the toe plate - but both ways are uncommon. There is always debate about whether or not this was done by the gun's builder or done later after wood shrank or broke, or to protect the toe etc., but some of them seem to me to have been obviously done by the builder - the "nicely done" one I described above seemed likely to have been done by the builder, part function, part design element.
For those of you that are hung up on Northern guns, check out some of Andrew Figthorn's guns, there are several that show this feature, one in Kindig's book if I remember right.
Not to stray from Roger's question, but any of you who are interested in seeing some of these neat Southern rifles up close and personal, some great examples have been making appearances at the CLA show in Lexington as a part of the antique guns and items portion of the event. Coming up sooner is the Tennessee Kentucky Rifle Show toward the end of April, that's a great show for seeing some things that don't turn up at many of the other events. I'd also recommend Ray McKnight's video and Jerry Noble's books. Information on all these is probably somewhere here on ALR if you do a search
