I've never used a Siler Mountain lock but I plan to eventually. I have used L&R's percussion lock that has the same plate profile as their Late English flintlock on a Bean rifle and was happy with it. I've also used their Manton and Egg percussion locks too, all of them were left handed. I am partial to L&R because they don't neglect us left handed shooters. Out of all of their locks, I like the little Manton lock the best.