THis has been a rahter educational thread- thank you all-
I was reading a pdf file from this forum that speaks to tuning of a Pietta and mentions checking the arbor length and a future article would address a remedy. By and large if the arbor was too long it could be filed down a bit in order to avoid the problem MCB mentions.
I had thought the 3rd gen Colt's were all made by Uberti but stamped by Colt- So now it appears they might have at least checked by Colt.
I may look into finding a 2nd gen just for grins though I will keep looking for a 1858 also.