I was at the range a couple days ago and noticed my handgun was shooting a couple inches high at 10 yards. Odd, I thought.
I put the target out to 25 yards and tried again. Yup, obviously high. I adjusted it down and continued my practice. It bothered me and I kept thinking about it.
Then I noticed the front sight looked a little odd. I looked closer and from a different angle and discovered the problem:
On the left is a new sight from my spare parts bin. On the right is the old sight.
I apparently broke it off shooting through a port at a recent match. To avoid damaging your gun you need to push all the way through the port or stay out of the port completely. If you are mostly centered in the port the recoil can interfere with the proper cycling and, as in this case, damage you gun.
I replaced the sight when I got home, order a new one to put in the spare parts bin, and went back to the range the next day to rezero my gun:
The top group is from five yards and the bottom group is from 27 yards away. One flyer with each six shot group but good enough to believe the sights are where they belong.