All of the DAs like this one are considered pre-1899, including the Frontier. No doubt about that.

S&W DA First Model revolver, all are pre-1899
S&W DA "Frontier" revolvers, all are pre-1899
S&W DA "Favorite" revolvers, all are pre-1899

All of the *frames* for the large frame top-break S&W's were made prior to 1899, and hence all New Model #3's, .44 DA 1st Models, DA Frontiers, and related models are considered "antique" by the ATF, even though they may have been cataloged and even assembled well into the early 20th century.