I put an RPL 5 on my GPR. I used Oxpho Blue Cream to closely match the color of the barrel. It's pretty easy to use and durable. Available on Amazon and Brownells.
I disassembled the lock and blued each part separately, filed to clean up parting lines before hand. Acetone to remove any...
This was 25 yards. Really just a function check. I'm having a hard time seeing the sights. Rear sight is in pretty good focus but I can't see the front blade. At this point, I think I need to change the sights to see if I can get a better picture. Could use suggestions in this regard.
I've been working on re-tooling and re-organizing my shop. Sold tablesaw, bandsaw, and drill press. Shopsmith Mark 7 on the way to replace them.
Tuning up dust collection with 2 stage system. Adding shelving, and throwing out the junk. Basically re-imaging my tiny 12x16 shop.