The common approach would be to not have them for the early 70's , 71, 72, 73 maybe even 74. Why?
You decide when cart. revolvers where truly prevalent. SW / REM conversions, Richards1871, 1872, 1873 then the Richard/Masons in 1874, then Rem 1975.
Before that and still during that period the most common revolver (major manuf.) were precussions. Not everyone could afford to convert or buy new. The 70's were the great depression years in America.
The loops aren't wrong just would advise also using a narrow belt ~1 1/2".
Just what I like or see in photos. Look in the book Packing Iron. Also read some of Marlan Ingrams authenticity articles in the Shootist.
Hope this helps you. It is not a difinitive answer but a way to look at it.
Black River Smith