Coles, Allems does a really nice roller setup, and there is a guy in Texas, but I cant remember his name
Phillip Crenwelge is one the finest Smith's in the country! He is in Emory,Texas. Google him and his number will pop right up. He did my double releases in my 682x and I am extremely happy with them.
I had Phillips Gunsmithing put in a mechanical release pull in my 686 the does a super job and only cost me $300.00 plus shipping.