got my Sept/Oct American Handgunner last night.
on page 105 they discuss the RM380 and mention rohrbaugh's connection (including saying they handled the R9 and "loved every one of them").
plus that the RM380 will retail for $417 and that "Now gents, how about a 9mm version? We know it can be done, as Rohrbaugh had one!"
FYI - 1953 here too....