Sir, as you may or may not know, Ruger has reneged on the 10-year provision of spares ethic for the ROA and there are no longer ANY spares for the Ruger Old Army that are not common to the Blackhawk revolver. I bought the last EVER set of rear-frame screws early last year, and was trying to set up a manufacturer here in UK to make replacement cylinder base pins, to no avail - there were not enough takers to make it economically-feasible.
I'm over in the states in a month or so and I'll be buying every part that I can find, but I know that there are no nipples out there.
I replaced mine last month with Treso nipples.
tac