I was trying out a couple of pistols and I was awful with both......but awful in two different directions. I decided to take myself out of the situation by building a support so I can adjust the sights.......then If I'm still awful....I know its me.
Here is what I came up with......and its made from scrap metal.
Here is what I came up with......and its made from scrap metal.

your best covering it with some foam rubber hold the gun in your hand and just rest the barrel end on the steady
then do a 5 shot test to see where the groupings are then re adjust and try again
One of my neighbours used to have a Dirty Harry Magnum and frankly I was a bit relieved when they took it as he was not the sanest of people.
A bad workman blames his tools