Practical Hunting Trajectory
THESE DAYS WE ARE INUNDATED with devices of all kinds that will tell us the exact range to a target, the wind speed at the muzzle of our rifle, angle up and down, elevation, even barometric pressure.Also, phone apps will tell us everything else we need to know.
The trouble with this is that in actual hunting scenarios we seldom have the time to drag out our rangefinder and phone to make the necessary calculations. Even scopes with added ballistic crosshairs are not quick enough in many such cases.
Therefore, we must be able to make a reasonably long shot, as quickly as possible, without having to dope it out, make adjustments on our scope or figure out which aiming point to use. Even taping your load’s trajectory to the stock of your rifle is not sufficient. The way to handle this is by sighting in our rifles at the longest possible range that will not cause mid-range misses.
Most rifles, if sighted-in to zero at 100 yards, will start to fall below the kill zone of a deer at from 150 to 200 yards. So it should be obvious that sighting Ol’ Blaster dead center at 100 yards is not the way to go. There is, however, a way to sight in that will give you the utmost range your rig is capable of without having to change the sight setting.
With a scope-sighted rifle firing a spritzer-shaped bullet at from 2,700 to above 3,200 fps, the best way I know to sight-in is a method I first saw in Jack O’Connor’s book The Big Game Rifle, published in 1952. That is to set your sights to put the bullet three inches high at 100 yards. This will, generally speaking, put the bullet about three or four inches high at 150 and 200 yards, and it will drop down from there. With this zero, you can put the crosshairs on the middle of a buck and hit it in the vitals out to ranges of from about 300 to as much as 400 yards. Again, this depends on the velocity, sectional density, and ballistic coefficient of your bullet and the size of the kill zone of your quarry.
With a .308 and 165-grain Nosler AccuBond bullets at 2,700 fps, your trajectory would be as follows: Three inches high at 100, 2.2 inches high at 200, dead center (or nearly so) at 250, and five inches low at 300. This will allow you to hold center on a deer’s chest and kill it at any range from 50 yards to almost 300. If, for instance, you had sighted-in to be dead on at 200 yards your trajectory would be two inches high at 100 and 8.7 inches low at 300, which could cause a low miss at 300 with a center hold.
A .270 Winchester with a 130-grain Nosler AccuBond bullet at 3,100 fps would have the following trajectory: three inches high at 100, 3.7 high at 150, 3.4 high at 200, 1.8 high at 250, 1.1 low at 300, and 5.3 low at 350. That is nearly 350 yards of point blank range on a deer-sized animal.
I have no idea how many deer I have killed with this sighting by simply holding on the center of their chests and shooting. Some I hit a bit high, but they were all dead deer.
A real hotrod like a 7mm Weatherby with a 140-grain AccuBond at 3,350 fps would give you even greater range. three inches high at 100, four inches high at 150 and 200, 3.1 high at 250, 1.1 high at 300, two inches low at 350, and only 6.4 low at 400.
As you can see from the above, by sighting in your hunting rifle three inches high at 100 yards, you will have the maximum point blank range that it is possible to get from your gun without causing mid-range misses.
A deer’s kill zone is something like 10 or 11 inches square so a four-inch rise at mid-range is not too much. I have used this sighting now for more than 40 years and have never lost a deer because I over-shot it at mid-range. I have, however, killed deer at fairly long and undetermined range that I would have missed if I had sighted in at shorter range, or if I had used the old standard of sighting in to be only one inch high at 100 yards.
The longest shot I ever made on a deer was successful because I used this sighting. It was 346 yards, as measured later with a laser rangefinder. I was shooting a very accurate .25-06 using 100-grain Barnes X bullets at nearly 3,400 fps. At that range, with that load, I was only about two inches low. I held on the deer and killed it, without knowing exactly how far it was. Had I sighted in at a shorter range I would have either missed it, or been forced to guess the range and hold accordingly, and my internal range guesser is extremely fallible. How is yours?
Email Steve LaMascus at ContactUs@fishgame.com