The problem forever with the 1377 (not so much the 1322) is the rear sight block is too tall when compared to other handgun rear sight units which sit barely above the surface of the receiver in a dovetail. In fact, most hand gun units are actually let into the body of the receiver flush, with just the notch blade sat above the receiver. On the Crosman, this already tall unit (relatively speaking) is then fixed above the barrel on the rear bolt housing….Taken together, it might just be the tallest rear sight ever fitted to a hand gun.
This usually does not prove a problem with the 1322 at 20 yds due to shooting pellets of almost twice the weight, with a more curved trajectory.
Best idea is to go with a bolt on sighting aid, such as red dots which have limitless adjustment, or try some of these new ultra heavy hunting slugs.