I very seldom post on this portion of the Colt Forum and usually am in the SAA Forum. I do have a Colt Walker 3rd Gen which I bought new but rarely shoot. I’ve never seen this specifically addressed anywhere but when the Army ordered the first thousand along with each pistol there was a combination tool which had a screwdriver on one end and if memory serves, a nipple wrench on the other. The body had a triple right angle bend that I once read was for main spring installation. I have a replica tool and I’ve always assumed that the “U” was used to compress the main spring but I don’t really know that. Most of you here know more than I do so exactly how was it employed?