In defense of the Pietta "tail"
First, I'm no Colt expert. I am a good observer and have a few good reference books.
I'm going to take exception to the common wisdom that Uberti 51's have the correct grip shape and Pietta 51's have too much tail.
In looking at lots of pictures of old Colts, I find both the Pietta and Uberti grip shapes to be correct.
The Pietta is more what is on the earlier 51's while the Uberti mimics the later 51's that became the grip on the 1873 SAA.
I've attached some pics of pictures from Swayze's "51 Colt Navies" book to illustrate the Colt "tail" correctly replicated by Pietta.
So don't feel the need to correct the Pietta tail unless you want to replicate the later Colt grip.