A few months ago I bought a 3" and a 5" 686 3-5-7 series revolver. I shot them for the first time a few weeks ago and both were shooting low using .38 Specials, the 5" lower than the 3".

So, I went back today, with this rest

so that I could sight the gun in properly. The first shot out of the 5" gun was about 12" low with .38 Specials and the 3" gun about 6" low at 25 yards. There was just enough adjustment to get the 5" into the bulls eye. .357 Magnums were grouping about 1 1/2" higher and right. It took a little over double the height adjustment to the 5 inch gun compared to the 3 inch gun.

Now this may be a dumb question but, as far as sight alignment, I was keeping the top to the front and rear sight level. Should I be keeping the bottom of the red in the front sight even with the top of the rear sight? By aiming that way it would seen to help the situation. Anybody else have a 686 that shoots like this?