Holsterguy, I do not know. You would have to call and ask. My guess: When Cimarron first started carrying the Piettas, the barrels said "FRONTIER" on the left side of the barrel in a large font. Later they dropped that stamping. Possibly the Frontier barrels are ones with that stamping. Personally, I hated that! Now, whether they have any in stock is another question. Good luck.
oh, and the bore, I think they are using .429 but wouldn't swear to it.