I am not sure what the distance is from the axis of the barrel of the top of the factory open rear sight is, but believe it to be generally from 3/4" to 7/8" high. The XS aperture shown puts the center of the aperture at about 1" above the bore axis. The Ultra Dot's axis is approximately 1-1/2" above the bore axis.
I have not had trouble with the Ultra Dot's height on this carbine, but would not want it any higher, thus the use of the 25mm (1") version over a 30mm version, and the regular low rings vs the QD rings. About another 1/4" higher and I would start to consider getting a lace-on gizmo to get the comb of the stock higher.
gn
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