There are a number of items in pistol shooting that are very different than long guns. The platform is not nearly as stable amking accurate shooting harder. Another thing is that the bore axis is well above the point of support. This causes the muzzle to rotate upwards when fired. Faster ammunition often strikes lower on the target since there is not as much time for the gun to rotate upward before the bullet exits. Slower ammunition often strikes higher on the target for the same reason, more bore time allowing the gn to move further.
If you have never fired a handgun extensively you might consider getting a .22. The ammunition is cheaper then even handloads, adn it is an excellent way to learn the ins and outs of accurate pistol shooting before having to deal with the recoil of a larger gun.