Shooting from sandbags, especially with a pistol, is not as easy as it may sound at first. It requires proper technique to get good results.
Proper positioning of the pistol on the bags is critical. There can be no movement and the shooter's grip has to be comfortable and repeatable. The gun has to rest on the bags the same way each time. The trigger must be pressed without moving the gun and exact sight alignment and positioning on the target must be maintained.
I use an aperature on my shooting glasses to sharpen the sight picture when shooting from a bench. Using these methods I can usually get 1.5 to 2.5 inch groups at 25 yards with almost any good pistol and ammo. I've had a rare few that would group tighter. I have a target fired with a 2x scoped Ruger Redhawk that measures 2 1/2 inches for 5 shots at 100 yards!
Shooting from sandbags, as with any type of shooting, requires proper technique and practice. I've been doing it for over 20 years.
Mikey