Thursday, July 26, 2007

In order to answer this question the first thing I had to do was see how small an object a radar gun could pick up. Since most chronographs are used for shooting sports and archery, I chose a subject roughly the size of the projectile from a 45 ACP cartridge. I chose this caliber, because it is a large projectile for handguns and it travels at a relatively low speed. In this case, I just happened to have a bag of Lemonheads sitting on the desk next to me. Explaining to the owner of the Lemonheads what I intended to do, he gratefully agreed to chuck the Lemonheads at me as I attempted to clock them with my Bushnell Speedster II Radar Gun. Surprisingly, the radar gun was able to pick up the Lemonheads traveling at 21 mph before they hit me square in the chest. Conclusion number 1: A radargun can pick up objects as small as common caliber bullets.

The next thing I had to test was the speeds involved in shooting sports. Radar guns are rated in mph or kph. Ammunition and arrows are rated in feet per second (fps). Some simple calculations bring out a simple conversion to go from one to the other.

fps x .6816 = mph

Most radar guns, including my Bushnell Speedster II, top out at 200 mph. Using the above formula, this translates to 293.43 fps. The most common load of 45 ACP ammunition is 850 fps. Without question, this is much faster than the radar gun will measure. However, the average velocity of bows for hunting is around 300 fps. The Bushnell Speedster Radargun will probably measure the speed about half the bows out there. The Decatur Prospeed CR-1k Radar Gun will measure speeds up to 310 mph. This figures out to be 454.8 fps. This unit will read the speeds of almost any hunting bow. However, when you compare its price of almost $800 to a common chronograph at $100, it just doesn’t make any sense.

In conclusion, you can use a radar gun as an archery chronograph, but it probably isn’t worth the cost. Have fun playing with them, though.

Ryan