I have a Uberti 1861 and a Pietta 1861 with brass TG and bs -- and the longer barrel. I happen to like both.
I was unaware the 1861 has ever had a squareback TG. Is that a repro of an actual Colt design or is it the Italian makers getting cute, like with .44 cal Navy 1851s?
I have the 1851 Navy Uberti with a squareback and it IS a little different -- atleast with me it crowds the middle finger a bit.
Both those guns look quite attractive BTW. Good find there, Strawhat!