Friday, September 21, 2012
Hunting rifle accuracy
How accurate is accurate enough? Depends on what is being shot and at what distance. Shoot as though the first shot will be the only shot.
There is inherent rifle accuracy, hunter’s marksmanship accuracy and actual delivered accuracy. Only the actual delivered accuracy matters at the moment of truth. The bullet simply must hit the kill zone to be successful.
The discussion here will assume shots by the individual hunter from field hunting positions.
When it comes to inherent rifle accuracy, minute-of-angle is considered good. Minute-of-angle is more or less one inch at 100 yards.
Certainly an inch or better grouping at 100 yards is sufficient for most hunting at most hunting shot distances. Just about any size group can work if the distance of the shot with that size group delivers the bullet to the kill zone every time.
GOOD GROUP?
DEPENDS ON THE DISTANCE — This is a 100-yard group shot by a rifle
chambered for the .30/30 Winchester cartridge. It’s an inch and a half
or so, which makes it totally valid for deer at that distance. The
bullet at the moment of truth must hit the kill zone, and any of the
five shots in this group would have done the trick. Even though the
actual group may string for close to two inches end-to-end, no single
shot is more than an inch and a half from the aiming point.
Average group sizes really don’t tell us much. We need to be more aware of extremes. It is about probabilities. We know where all of the previous bullets have gone. But we need to be comfortable with where the next one will go.
Group sizes generally are discussed as the diameter of a group. For hunting, radius is more useful. If the bullet does not hit the precise point where the hunter wants it to go, the important measurement is how far from that imaginary point does the bullet actually hit?
For deer size animals, that maximum distance is usually four or five inches in about any direction, and sometimes as much as six in some directions.
Assuming that, we have just established the minimum effective accuracy for success: a rig/hunter that will deliver the bullet no more than four or five inches from the intended/ideal impact point. Maximum distance is how far the shot is when that number is met but not exceeded.
Next step is to shoot the rig a number of times (like a dozen or two is nice) and record the extreme distances from the desired impact point. Shots in between don’t count.
If the practice shots are at 100 yards and if the extreme distance for any shot (include fliers, everything) from the intended point is four to five inches, then that rig CAN be valid at that distance.
We can extrapolate a bit, but rarely is a group only twice as big at 200 yards as it was at 100 yards (usually there is a fudge factor that makes actual groups grow a bit more than linear measurement would suggest).
So, it is always nice to verify things at the various distances. Suffice it to say, however, that a 1 MOA rig likely will remain valid at least to 300 yards.
With these very rudimentary measurements, it is fairly simple to determine the accuracy effective distance of a hunting rifle/hunter.
Some are pushing the limits at 50 yards, while others are valid way out there. Once the maximum effective distance is known, merely limit shots to that distance or less.
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Steve Comus is a nationally recognized hunting editor with Safari Club International and a former WON Guns and Hunting Editor. His column appears every other week in WON and he can be reached at scomus@cox.net.
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