Crosman .177-cal. steel breech kit Fits Crosman airgun models 1377,* 1740, 1760 and PC77 Will accept the Crosman LPA MIM rear sight * The original rear sight that comes with any of these airgun models will no longer fit on the steel breech. If you want a rear sight, the Crosman LPA MIM rear sight is made for this kit (CR-2300-010[PY-A-4385]).* *This breech does not fit older model 1377 air pistols with a sliding breech cover.