3 screw trigger frame??

[mcc1961]

Why does my 1377 have a 3 screw trigger frame.I think it came from Wally World?

[Crosshairs]

Crosman changed the frame a few years ago.
                                 Mike

[Noah]

Aware of the two to three screw trigger frame change a while back, but I am still wondering WHY this change was made. Suddenly a few of my grips are not interchangable with other frames which is no huge loss, but still, WHY was this change made?