I've got three 1377s and all are the older model.

The only thing I'd say is that the older ones do not have bolts - you slide back the breech cover, insert a pellet and then prime it by pulling the knob (ooer missus) on the end. This is no big deal but is a bit fiddly compared to the bolt and it is easy to get the pellet in sideways if you are not careful.