Long post, applicable only to pistols shot with some view towards combining speed and accuracy.
Firmness of grip is essential to effective recoil control in handguns
if we care about time to 2nd shot. Firmness in grip with the weak/support hand can also cover up a bit of sloppiness in trigger press, but it's not otherwise related directly to accuracy itself. If you get into competitive action/practical pistol shooting, where being able to control the gun effectively while firing a lot of shots in the shortest amount of time you can manage is essential to the game, you will find a decent correlation between grip strength and performance.
Assuming this is the type of shooting we're talking about (whether for competition or self-defense), then, yeah, having a significant amount of hand strength is beneficial. Because it's hard to maintain fine motor control (despite blather about trying to use "gross motor skills" for handgun shooting, it's pretty much
all fine motor control) when you're exerting 100% effort, you want a sufficient "excess" amount of strength to be able to apply a good deal of force to the grip of the gun while still only using about 80% of your strong-hand grip strength.
Most adult males in good health and with any kind of active lifestyle often have something like enough grip strength in their dominant hand without a lot of special training focus on grip strength. But many, many, many otherwise-strong people don't have nearly enough in their
non-dominant hand. That's unfortunate, because, when it comes to freestyle pistol shooting, effective recoil control is driven more by the
non-dominant hand than by the "strong" hand. Because of the location of the strong hand and the design of most pistols, the forearm ends up roughly behind the grip, and the 3-non-trigger fingers have direct access to the front strap of the gun. There's lots of
interference fit between the gun and the right hand.
In contrast, the left hand is almost all dependent on a
friction fit to apply any force to the gun. It is very common to see shooters whose pistol moves relative to their left hand in recoil - which means the gun is slipping from their grasp, and the left hand is adding little or nothing to recoil control. This is certainly one of the most common errors among new-to-USPSA/IPSC shooters, and it makes the kinds of split and transition times you want in that game absolutely impossible (at least while keeping shots after the first one anywhere near the target).
If you have doubt about whether this is happening, go shoot a "bill drill" at a close target. Rip 6 shots as fast as you can pull the trigger into a target. If possible, have someone video you from your left (if you are right handed) with a focus on the gun and your grip. At the end of the 6 shots, if you feel the need to re-grip the gun or if your left hand is arranged any differently than it was at the start of the 6 shots, then you are not gripping the gun effectively with your left hand. There can be basically 4 causes of this: 1) application of an insufficient percentage of available weak-hand strength; 2) lack of adequate available weak-hand strength; 3) lack of area of contact between the left hand and the gun; and/or 4) actual slipperiness of the grip.
Each has its own solution:
- Consciously grip harder with the weak hand. Squeeze as hard as you can. Unlike with the firing hand, where you need to maintain some level of relaxation for trigger speed and precision, you're not asking for much dexterity from the left hand, so there's no tradeoff (other than effort) for gripping harder.
- If you're already gripping as hard as you can, and you've eliminated #3 and #4 below, then it is essential to get more grip strength. You need to embark on some sort of grip-strengthening program, with particular attention to your weak hand. Suggestions are below.
- Lots of people fail to get an effective amount of left-hand flesh onto the gun. One common cause of this is having the right hand thumb curled down onto the grip. This serves only to block the most important contact area for the left hand - the upper portion of the grip panels or stippled area. Many people instinctively curl their strong-hand thumb down, as though they were making a fist, when they grip the gun. While this is sometimes necessary with revolvers, it is a distinctly sub-optimal way to grip a semi-automatic pistol. Even if your particular gun doesn't have a 1911-ish safety to ride, your right thumb should still be in about the same location/orientation is as if were riding the safety if you are trying to maximize recoil control through the use of the left hand. I see lots of new-to-competition shooters who have totally ineffective recoil control because their right thumb is basically forcing the heel of their left hand off the gun laterally. The gun goes off, the gun and right hand move together, and the left hand slides down the grip. After a couple of shots, they're re-gripping. May as well shoot Barney Miller teacup style for all the recoil control the left hand is providing (i.e., none whatsoever).
- Sometimes, grips just don't have much of a coefficient of static friction. If you combine that with sweaty hands, it's like trying to hold onto an inside-out banana. Effective checkering or texture matters in grips, particularly on the left side where friction is essential. If the grips are slick, replace them or checker/stipple them, or get some skateboard tape on there.
OK, let's say you've decided to build hand strength, particularly in your weak-hand. How do you do it? Here are
some suggestions:
- Conventional grip trainers are effective, although a lot of the ones available at sporting goods stores are simply too soft to be effective for getting to the levels of grip strength we want. The Ironmind CoC ones are good, but they can be just slightly too rough and, for some, too stiff. I happen to like the Ironmind Excelsior grip trainers - similar to the CoC (and same maker), they have smooth handles that won't wear out your skin, and run about a half-step softer than the equivalent CoC trainers (e.g., an Excelsior #2 seems to be between a #1 and #2 CoC). A #1 from either series is sufficiently stiff to serve the vast majority of people. I keep an Excelsior #1 and #2 in my office and use them on conference calls! I find that most men can close the #1 with their strong hand, but a good many cannot do it, or can only do it once or twice with their weak hand.
- It helps to get a grip dyno (a device that measures squeezing force) to track progress. Here's a cheap one: https://www.amazon.com/CAMRY-Dynamometer-Strength-Measurement-Capturing/dp/B00A8K4L84/ref=sr_1_1_sspa?crid=5YQNNQ7MOPCD&keywords=camry+grip+strength&qid=1561643438&s=gateway&sprefix=camry+gri,aps,166&sr=8-1-spons&psc=1 I have one and like it. It has held up to several years of use. It's fun to take it to a shooting match and have people grip it... you may notice the correlation I mentioned above between grip strength and shooters with better recoil control.
- Hand and forearm muscles are small. The good news is that their relatively small size makes recovery quick. If you work your forearms to the point of fatigue, they will likely be recovered by the next day. It's also possible to add strength pretty quickly. I think you can add 20% to your gripping strength faster than you can quickly add 20% to your bench press, for instance. The bad news is that these small muscles atrophy pretty quickly if not used. If you stop working them, you'll go back to near-baseline grip strength really, really fast.
- There are other hand and forearm muscles to be trained other than the ones used for closing a grip trainer, and there is some "unbalancing" injury risk in training only the contractor muscles. And additional dimensions of strength can only help. So here are some other things to add to the grip-training regimen:
- Bring your thumb and fingertips together to a single point - as if you were grasping a pen to write, but with all 5 digits, not just 2-3. Put a rubber band around them, and open (and close) the fingers against this resistance. This is working the extensor action that is opposite the contractor action of the grip trainer. Just a few reps may tire your forearms out, but some think this provides some protection against injury from the contractor training.
- Using light dumbells: Brace your forearms on your thighs while seated. Grasp the dumbells palm up, and roll your whole hand (and the weight) upward (almost like making a come-here motion with your hand). Do a few of those, then flip to a palms-down orientation. Raise the dumbell (almost like making a stop-traffic motion with your hand). Some contend this is a good preventative measure against tendonitis/shooter's elbow.
- Using a pair of baseball bats, stand with your hands by your sides. Grasp the bats at the end of the handle like you were grabbing ski-poles/walking sticks. Keeping your arms against your sides, using only your wrists, pivot the bats upward through an arc until they touch (or nearly touch) your rear shoulder blades. Lower them and repeat. After doing enough of these to feel fatigue in your forearms and hands, turn the bats around, and raise them through a forward arc to your pectorals - again, with your arms locked at your sides. These exercises are good for strengthening the muscles involved in "locking the wrist."
- Lots of weak-hand strengthening (and dexterity training, good for one-handed weak-hand shooting) can be done by simply forcing yourself to do common one-handed tasks with your off hand (alright, settle down in the back of the class there). Next time you need to use a screwdriver, use your weak hand. Dial phone numbers on with your left hand. Comb your hair or brush your teeth with your left hand. Your hands have lots of little muscles in them, and the fine motor control demands of these tasks will strengthen them. It will also condition you to the feeling of focusing your attention on your weak hand and using it.
- Unfortunately, pretty much everyone who does grip training, or otherwise uses lots of grip strength, ends up with occasional visits from the tendonitis fairy. There may well be times you just have to set this stuff aside for a week or two.
- I think Charlie Perez is one of the most thoughtful shooters on this topic. If this stuff is of any interest to you, you may want to search for videos or posts (he posts at the Brian Enos forums under the CHA-LEE screen name) he has made about this subject. Suffice it to say, he takes grip training seriously, and has world class recoil control with pistols.