Here's something I wrote on the subject:
Rifle shooters love benchrests, and so do ammunition manufacturers. Probably half the rifle ammo in the U.S.A. gets touched off by humans sitting behind a bench. Americans really like instant gratification, whether staring at our smart phone or trying to hit a target, and apparently hitting a bullseye every time feels as sweet as surfing the Net in a restaurant.
Handloaders often use benchrests to determine the MOST ACCURATE powder charge and bullet. Unfortunately, relatively few handloaders hold the rifle the same way from shot to shot. As a result tiny target-clusters are usually accidents, the primary reason “test” groups shrank from five shots to three during the past century: Three shots stand a far better chance of landing inside the magic half-inch, whereupon the shooter declares he has a “half-inch load” and carries the magic group in his wallet.
If you’d like to shoot tiny groups more often, here are some basics:
First, if the range doesn’t have any wind-flags, set up some sort of flag yourself. Competitive benchrest shooters use pretty fancy flags, but a strip of surveyor’s tape tied to a stick is better than nothing. Try to shoot when the flag’s waving the same way.
Make sure you’re sitting comfortably, and holding the rifle with as little strain as possible. If you need to force the rifle to line up on the target, then you’re likely to relax as the trigger breaks, shifting the rifle slightly as the bullet starts down the barrel. Rearrange the front and rear rests until the scope rests naturally on the target, the major reason for an adjustable-height front rest. (No, a stack of scrap 2x4’s does not qualify as an adjustable rest.)
Next, move your head back and forth behind the scope. If the reticle apparently moves back and forth across the target, that’s parallax, and some shots may land off-center even if you don’t flinch. If your scope has an adjustable objective lens or side-focus dial, look through the scope while turning the lens or dial, until the reticle doesn’t move on the target when you move your head. (Pay no attention to the numbers on the adjustment; 90% of the time they’re decorative, or what passes for decorative among gun guys.)
If the scope can’t be adjusted for parallax, move your head back until a black ring appears around the field-of-view, then keep the reticle centered inside the black ring when aiming. This minimizes parallax, because you’re always looking through the center of the scope.
Hold the rifle the same way for every shot, including the position and pressure of your hand around the grip, cheekbone on the comb, and butt against your shoulder. Place the forend on the front rest in the same place, with the front sling swivel stud at least couple inches in front of the sandbag, so the stud doesn’t slam into the rest during recoil, causing a mysterious “flier” and ruining a wallet-group. Most bench shooters don’t hold the forend, but when testing a hard-kicker it helps to hold the forend firmly just behind the front rest, a trick learned from reading Elmer Keith.
As a final check before shooting, place the reticle on the bullseye and dry-fire a few times. If the reticle shifts position after the click, you’re not holding the rifle consistently—or moving slightly after pulling the trigger. Many shooters unconsciously jerk their finger away from the trigger as soon the shot fires, a fault my friends at the FTW Ranch in Texas call “booger-flicking.”
Real benchrest shooters, who shoot tiny groups during the stress of competition, often don’t touch the rifle except with their trigger finger. Most hunters, however, are testing handloads or sighting-in, so need to hold the rifle about the same way we would in the field.
When shooting prone this often involves a bipod, or resting the forend on a pack. I use a fleece daypack stuffed full of lunch, spare clothes, a signal/shelter tarp, and a thick paperback book, in case I get lost and need to wait for somebody to find me. (So far I haven’t been lost that long.)
A harder rest, even a well-compressed sandbag, can increase group size, especially with the lightweight rifles many hunters prefer these days. When bench-testing lightweights, I fold a terry-cloth towel and drape it over the front rest, simulating my day-pack. Lead Sleds can also cause a rifle to shoot to a different point-of-impact, so after sighting-in try a few rounds without the sled.
Many shooters experiment with forend placement on the front bag, to find where the rifle “shoots best.” If you’re at the range for Saturday recreation this can add to the fun, and even result in wallet-groups. But I’ve lost count of how many forend-experimenters claim their rifle shoots best when rested on the front action screw, not the forend. Here’s a clue, dudes: There’s something screwy with the forend bedding.
