subtract the two and divide that number by 290 feet. Let us suppose the velocity at 100 yards is 2,617 fps and the velocity at the chrono shows 2,750. So 2,750 – 2,617 = a 133 fps loss between the muzzle and the chronograph. 133 fps ÷ 290 feet = 0.46 loss per foot. To get the muzzle velocity, add 10 more feet to the muzzle velocity by multiplying 99 shots, Operating temperature: -4 to 10 x 0.46 = 4.6 feet. Now add that to 158 F, Price: $368 Math CorreCtionS the chronograph reading and it raises Shooting those longer ranges, you muzzle velocity to 2,755 fps. Maybe not tweak your favorite ballistic software to match your hits at enough to worry about, but a 25 fps spread can result in those long ranges until they match up. It might be you have about 1 MOA change at 1,000 yards—a 10-inch difference. to enter a velocity in the ballistic software slightly different You also have to worry about lift at that range, which than your chronograph shows. Remember, if you have set the means the bullet will rise about 3 inches at 1,000 yards chrono up 10 feet from the muzzle, you have to back calcu- in a right-to-left wind and fall about 3 inches in a leftlate what the velocity is at the muzzle. to-right wind. You are now 3 inches low or high without First, look at the velocity the ballistic any other variables entering the equation. For example, program gives you at 100 yards and at the in a full 10 mph wind from right to left, the bullet will chronograph, move 57.5 inches to the left and 3 inches high at 1,000 yards. But will it be a full 10 mph wind over the entire 1,000 yards? It might be 10 mph at the muzzle and 5 mph in the opposite direction at 600 yards. To make matters even worse, you have both spindrift and Coriolis force to worry about as the distance increases. And for the latter, it even matters what direction you aim or what hemisphere you are in. Are you beginning to realize a first-round hit at 1,000 or more yards is very difficult, maybe impossible? Of course this depends on the size of the target. Not too difficult to hit a barn, but a 24-inch steel gong is troublesome. To further complicate the issue, you are faced with 60 feet elevation and 75 degrees F at your testing site, but more like 6,500 feet elevation and 30 degrees, or 4,000 feet and 0 degrees, or 11,000 feet and -20 degrees F at your hunting site. You begin printing out charts of possible The SuperChrono is small environmental conditions and soon realenough to take anywhere, requires nothing more ize you’ll have too many sheets to deal than what you see here with. You need a handheld computer and is very accurate when like an iPhone, iPOD, or iPAC or used per the directions. something. Again, we have to deal with making it match what we have tweaked at long range. Then it occurs to you there is no WWW.GUNSMAGAZINE.COM 59 Since this is just hypothetical, let’s suppose those firstround hits are more like 5 inches, but the group is still in the bull. Your scope has both hashmarks every 2 MOA (maybe mils) and enough elevation range in the target turret to get you beyond 1,000 yards without difficulty. If not, you may need another scope, a shim under the rear portion of the mount, etc. You now proceed to try your hand shooting at 700, 800, 900, 1,000 yards or more. To do this you need to know the come-ups at those ranges, and you do so with the ballistic software. In fact, perhaps you’ve purchased three differSupeRChROnO ent programs developed by three differMaker: Steinert SenSing SySteM aS profeSSor dahlS gate 3 ent ballisticians. You find no matter o355 oSlo, norWay how you enter the variables of environWWW.SteinertSenSing.coM mental conditions, velocity, etc., they Type: Ultrasound microphones, show slightly different results after Sensor Detection: 10 inches to any distance all your work accomplished at 60 feet downrange, Velocity Range: 1,234 to elevation and temperatures approach- 5,632 fps, Size: 10.2 x 4.7 x 1.8 inches, Weight: 10 ounces, Maximum capacity: ing 80 degrees.