This .308 hit an inch higher with hand pressure on a rested rifle than one rested without hand pressure.

A sling tugging on a barrel stud can produce more dramatic effect, as it directly influences barrel vibration and can even bow the barrel.

Offhand without a sling there’s no pull but no solid support either. So the rifle can dip as you press the trigger. As the trigger breaks, tiring muscles can involuntarily give way. Typically, offhand shots land low.

Rifle support can affect accuracy, too, and not just because some forms of support allow more rifle movement than others. Resting a rifle on a rock sets up different vibrations upon firing than does a rest that cushions the rifle.

Resting it against the side of a tree bounces it horizontally instead of vertically and can thus change the shape as well as the size of your group. To minimize changes in group placement, size and shape, it makes sense to pad the fore-end with your hand, always in the same place.

While 40 years of shooting have verified coach Earl Wickman’s observations on position, only recently did I document changes in bullet strike resulting from changes in rifle support.

I chose three rifles and a rifled shotgun, punching five-shot groups from four positions: a commercial rest under the fore-end, gripping the stock’s wrist only; a commercial rest under the fore-end, gripping wrist and fore-end; a padded block under the barrel; and a tight sling in prone position.

The chart shows the results (the rifles were fired at 100 yards, shotgun at 75). Numbers show changes in group placement (zero) and group size (group) in inches.

A barrel-mounted swivel stud on a Ruger No. 1 in .375 contributes to low groups from a sling-assisted sitting position.

The .375 was fired only from a traditional rest and with a tight sling, for two reasons: First, with open sights I couldn’t be guaranteed the tight groups necessary to detect slight differences in accuracy and point of impact after changing only my grip.

Second, a .375 is unlikely to be fired with a hard rest under the barrel. The sling test was meaningful because this Ruger has a barrel-mounted swivel stud. I suspected its effect would be greater than that of a stud affixed to the fore-end.

The average depression from zero with a taut sling was three inches at 100 yards for the three sporter-weight rifles. Elevation boost from direct barrel pressure for these rifles tested averaged 1.6 inches.

The tightest group from the .22-250 came with the barrel rested. For this rifle, consistent contact apparently trumped no contact. Pulling the fore-end down onto the rest was as likely to bump a shot high as to depress point of impact--maybe for the same reason a basketball dribbled hard next to the floor bounces higher than does one dribbled gently.

Group sizes varied little, even with marked change in point of impact. The vertical stringing I had expected from the barrel rest did not happen. Indeed, changes in support did not alter group shape as much as I’d anticipated.

Variables that affect bullet response to changes in rifle support include barrel weight and bedding, ambient temperature, stock design and material, lock time, sling placement and tension, rest placement and firmness, wrist pressure from your hand, cheek pressure and, well, the list is long.

Conclusion? The only way to find out where your rifle is shooting from any position is to fire a group or two from that position. Fire at least five per group. Repeat with a clean bore if you’re a hunter, because you’ll likely be firing the most important shot from a clean bore. Shoot from the positions you’ll likely use on the hunt until you feel confident that the bullet will land at point of aim if you do your part.