From what I've seen over the years here in WI., the most common open sight installed on the 336 and similar rifles is the old Williams "peep" on the receiver, and no insert in the aperture. This setup wasn't much for putting a cloverleaf group on paper, but did a great job of getting the shooter on target when the 12 pointer ran out of the drive. Now it seems that if you don't have some kind of scope, you just aint in the game. I've experimented with, made, and used pretty much every open sight design. I like shooting with open sights, and sometimes feel that scoping a classic lever action .30-30 is like putting a two dollar saddle on a thoroughbred. Wondering what your thoughts are and the type of OPEN SIGHT you find best for whitetail or similar game.