Over the course of several years as a rangemaster and having attempted (key word here is ATTEMPTED) to sight in those stupid flip mounts, I can say without out a doubt that they're about as useful as a solar powered ashtray. They routinely don't hold POI and can't be trusted. I'm sure the ammo makers would love to see them on every deer rifle out there, as they'd sell one buttload of ammo. Conventional bases and rings, as low to the barrel as possible, (don't use extra high rings if you don't need to) and a good 4X scope are all a lever gun really needs. Pick open sights or use a scope. Don't try to combine both.
