Getting a proper grip on your gun is very important. Your gun must become an extension of your hand and arm as it replaces the finger in pointing at an object so proper gun grip is essential. Gun grip effects your sighting (aim), your balance, your ability to work the hammer (on a revolver) to pull the trigger, to work a safety mechanism (if your gun has one), to absorb much of the recoil with as little discomfort as possible and your safety. There are some slight differences between the proper grip for a revolver and that of a semiautomatic gun.
For self defense, a two handed gun grip is always better. It is however recommended to get comfortable gripping and shooting your gun one handed as well, in both dominant and non-dominant hands. This is in the event you are somehow disabled and forced to shoot one handed. So getting comfortable and proficient with a proper gun grip in both hands is necessary.
Finding the proper grip
As stated above, in self defense situations the preferred and proper gun grip is a two handed grip.
Because two hands are involved, each hand has it's own place and function in the grip. The support hand stabilizes the handgun and makes the shooter more accurate. You want a firm and solid gun grip for maximum control and accuracy. Don't be shy and offer your gun a limp handshake! Grab on and hold firmly!
The higher the hand on the grip (with the flesh of the web of your hand pressed up snug toward the top of the grip) and the straighter the alignment of the barrel of your gun and your arm, the better a "shock absorber" your hand and arm are. You can simply check to see if you have proper gun grip and straight alignment. As you look down over your arm - it should be a straight line from the butt of your gun (in the web between your thumb and index finger) that runs up to your elbow. You should not see and break in the wrist. You will be better able to handle recoil as your entire arm acts as a shock absorber. This also means you will have much better control over muzzle jump (the tendency for the barrel to rise quickly upon firing). If you have a break in this imaginary line, it is likely that the grip of the gun is too large for you hand. To accommodate a grip that is too large, you are forced to "adjust" the grip by moving your hand forward and around the grip, displacing the butt of the gun from the center of the webbed area between your thumb and index finger. Once you are off center, the shock absorber effect is greatly diminished as well as the quality of your grip. Another thing to consider is that if you are in the stressful situation of dealing with an attacker - you likely do not have the time or the mental capabilities to make awkward adjustments to your grip. When you grab the grip of your gun, it should place your hand in the perfect grip, one that is ready to raise the gun, aim and fire.
ANYTIME YOU GRIP YOUR GUN - YOUR TRIGGER FINGER MUST REMAIN STRAIGHT AND NOT ENTER THE TRIGGER GUARD. EXTENDED INDEX FINGER SHOULD LIE ALONG THE SIDE OF THE FRAME.
Proper Gun Grip For The Revolver
The proper gun grip for the revolver (whether for one handed or two handed grip) starts with placing the gun in your dominant hand with it pressed all the way into the web of your hand, high on the backstrap. The top of the barrel of the gun should be in line with your forearm which should be in line with the "V" created by your thumb and index finger. Your trigger finger lies flat along the frame of the gun and does not enter the trigger guard.
For Single Action revolver shooting, in which you must cock the hammer to chamber each round, the proper grip on your gun has your thumb placed high on the side of the frame so it is free and has easy access to cock the hammer.
For Double Action revolver shooting, in which there is either no external hammer to cock or cocking the hammer is not required, the grip is the same, but the proper gun grip has the thumb is dropped down to grasp the handle to provide maximum leverage for the longer, harder trigger pull of a double action revolver.
For a proper two handed grip, the second, non dominant hand simply will wrap firmly around the shooting hand. This steadies the grip, allows for proper trigger pull and helps to absorb recoil and prepare for another round. The thumb of the supporting hand can be placed on top of the strong hand thumb and in the case of a single action revolver, be used to pull the hammer back.
Proper Gun Grip For The Semi-automatic Gun
When a semiautomatic gun is fired, the slide will kick backward and forward with great power and speed, not a place you want your hand to be! Semiautomatic guns are designed to provide a shelf or hood that will keep your hand from crossing into this area. It is here that the proper gun grip for the semiautomatic gun is.
Again, the higher the hand on the grip and the straighter the alignment of the barrel of your gun and your arm, the better a "shock absorber" your hand and arm are and indicates a proper grip on your gun. This means you will have much better control over muzzle jump (the tendency for the barrel to rise quickly upon firing) and be better able you are to handle recoil. When gripping your semiautomatic pistol, you should see your flesh wrinkle some behind the backstrap and under the shelf or hood.
Photo courtesy of Simply About Guns
Here the proper gun grip for the semiautomatic is shown. The gun is placed into the "V" created and firmly into the web of your hand. Both thumbs on the same side. (left side of the gun if you are right handed) Your thumb is high and slightly curled downward to provide added grip strength and to rest on the safety mechanism (if your gun has one) for easy access. Your support hand thumb lies along the side below the slide action and pointing forward. Your trigger finger lies flat along the frame of the gun and does not enter the trigger guard.
A Proper Grip on your Gun Creates Stability for Shooting
With a firm and proper grip on your gun, you raise your arms to a firing position and will apply forward pressure (push) with the firing hand and pull rearward with the non-firing hand with equal pressure. This creates a stabilizing tension that steadies the gun and reduces barrel rise from recoil. The supporting arm is bent with the elbow pulled downward. The firing arm is fully extended with the elbow and wrist locked. As you practice, you will need to experiment with these two pressures to find the right amount pressure that works for you. But I guarantee you will feel a greater stability utilizing this "push-pull" tension.
Your gun will always be moving to one degree or another. No one, not even the best shooters can hold a gun perfectly still while they are shooting. A good strong proper grip and proper sight alignment will have the gun lined up on the target. Keep it in that zone and smoothly squeeze the trigger.
Here is a great video by Shannon Smith