My friend, ring gap is not the distance from 1st ring to top of piston. It is the distance(gap) between the start of the ring and the other end. It is what can be "adjusted" with file fit rings. It also is not the reason the compression is lower, that is the dome of the piston, which is also different than the 1st land(what I call top of piston to 1st ring). Sorry for the confusion.