large/small frame difference? [Archive] - Glock Talk

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BillR
07-14-2010, 09:18
On some sight sets, they state that the sights will "fit all Glocks". Others are frame specific. Why is there a difference?
On Amerigo's site, they list the front sight as a standard height for all Glocks. (.165) The rears are different by model, but I can't figure out why. Why would the rear sight need to be taller on a G20/21 than on a G17/22 if the front is the same height?

smoke
07-14-2010, 09:56
It is a POI/POA thing. The main reason the big frames have higher rear sights is because of the difference from the center of the bore to the top of the sights. In other words, the distance from the center of the bore to the top of the front sight on a G21 is higher because of the increased meat of the slide, since the sights are the same. If you used the same height rear sight as a G22, the gun would probably shoot low. The taller rear compensates for the difference by bringing the POI up.

BillR
07-14-2010, 10:02
It is a POI/POA thing. The main reason the big frames have higher rear sights is because of the difference from the center of the bore to the top of the sights. In other words, the distance from the center of the bore to the top of the front sight on a G21 is higher because of the increased meat of the slide, since the sights are the same. If you used the same height rear sight as a G22, the gun would probably shoot low. The taller rear compensates for the difference by bringing the POI up.

That makes sense!
Thanks for the explaination.:wavey: