A common precision rear sight for the No. 4 is the PH 5C, or AJ Parker equivalent. An alternative is to install a Central No. 4 sight, using a mounting plate. Attaching the plate does not require any modification to the rifle. Paul Reibin, at Range Sports Unlimited in BC has a Central sight, with 6-hole eyepiece for $100, and new made mounting plates as well. The Central can be used on just about any rifle with the appropriate base. Bases that fit a variety of rifles are available. The Central is at least the equal of the PH as far as quality goes.