I’ve got a 3” Round Butt Model 10. For the most part the 3” 10’s And 13’s, were un-cataloged, manufactured, as needed for specific agencies. NYSP and the FBI are examples of two agencies issuing the 3” heavy barreled models.

My 3” HB, RB, 10, is one of two, made in the mid 80’s. The other gun went to my friend. Their manufacture, is a story for another time. The 3” round butts are, IMO, very well balanced revolvers.