Going Shooting, Point Blank

Or at least trying to. Yesterday I was complertely prepared to participate in the club Rimfire Steel Dogs shoot but instead had to spend Saturday morning buying a new battery for the truck. Bummer.

The Steel Dog Shoot involves steel cutouts of prairie dogs set up at distances starting at 35 yards, and every 15 yards out to 150 yards. As I understand it you shoot this course 3 times, near to far, far to near, and near to far. You cannot shoot the next dog until you've hit the last one, and each course is timed. There may be more, I haven't been out to one yet.

150 yards is a bit of a reach for a .22, but not impossible by any means, and to do well, you must know your rifle. How do you adjust your sights, and what will give you the best results? I use a program called Point Blank which is available free here. My version was older, and I haven't tried the new one yet, but it's said that the new one is much better than the old one. Good.

You enter data from your gun (ideally) or from the ammo box, enter some physical data like the distance from the bore of the gun to the center line of the sight, and the ballistic coefficient of the bullets, along with the distance you plan to zero your sights at, and the program will print out a chart of the expected arc of your bullet, along with suggested windage corrections for any range you think you can reach.

So what's the ballistic coefficient, I hear you ask? It's the relationship your bullet has with the air its passing through. The number varies from about .1 to about .4 and the higher the BC, the flatter your bullet will fly. At shorter ranges, the effect is modest, but as you get out there over 200 yards, it becomes a significant factor.

For the .22 I was planning to use, the bullet box said the expected muzzle velocity would be 1280 fps, and convieniently also mentioned that the bullet would be making 1100 fps at 100 yards. Point Blank has an app in it that takes these 2 numbers and the caliber of your bullet, and gives the BC for the bullet. For this .22 ammo, the answer was .11.

Point blank, which probably ought to be points blank, is the two distances at which your bullet crosses your line of sight, first going up close in, and second going down, further out. If you're shooting at several ranges, you want your sights adjusted so that the rise up close is approximately equal to the drop at the extreme range. This minimizes the corrections you have to make to get the hit, and keeps the numbers you have to remember to a minimum. Less math is good.

Tell the program you will be setting your sights for 125 yards, and the program will tell you that you will be hitting 4.9" high at 70 yards, and 5.7 inches low at 150. Ask for the results to be in 10 yard intervals, and you find you're 2" high at 35 yards and between 4 and 4-3/4" high from 50 to 95, 2" high at 110, spot on at 125, and 5.5" low at 150. A prairie dog is about 8" tall, so aim for his navel up close, his feet out to 95, his navel again at 110, spot on at 125, and about an inch over his head at 150.

There's even a column for suggested windage allowances, and for light bullets like the .22, a 10 mph wind will put you nearly a foot off at 150 yards, considerably more than the bullet drop.

Our range has backstops every 25 yards out to 100, and every 100 yards out to 300. To sight the gun in without doing a lot of walking, use the 50 yard backstop, and put two dots on a paper plate with a fat marker, one near the bottom, and one 4-3/8" above it. If you aim at the bottom dot and hit the upper one, you're spot on for 125 yds.

The above data is true for my rifle, which has a scope mounted 1.5" above the barrel. If your scope is higher, or if your iron sights are lower, the results will be significantly different, so get the program and run it for your gun. At this point, you will know more about your gun than 90% of the folks out on the range, and will be making those long shots the others just dream about.