George Block Column

Measuring bullet speed getting easier

Measuring bullet speed getting easier

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It’s nothing but common sense. If two bullets of identical shape are fired from the same rifle at different velocities, the faster one will drop less.


Speed not only affects drop of a projectile but also increases the kinetic energy. A fast bullet will shoot more flat and hit harder than a slower one.


I was not only shooting for accuracy one day but also doing some work on the chronograph. There were two other shooters at the range that day, and I happened to know each.


One approached me and asked if I would chronograph his loads. I placed his rifle on the bags and sighted over the screens, squeezing the trigger on the .222.


Pat, the rifle’s owner, said his loads were a bit hot, but that he had used them for years. I looked at the results and saw 3,300 feet per second, very fast for that cartridge.


I could see that the other shooter was getting itchy and wanted to see a reading on his reloads as well.


Finally, he approached me and asked me to check the speed on his .22-250. He had dropped varmints at well over 500 yards with it, taking head shots.


As many know, the .22-250 is much larger than the .222 and should reach out a good bit farther. Not this one.


The load for the .22-250 was only moving at 3,250 fps. The .222 was faster.


Need I say more. The poor soul never hit another groundhog with it and soon sold the rifle. Perhaps a bit more powder would have helped. But sometimes we’re better off not knowing.


From that day, when asked to check a rifle, I always ask if the shooter really wants to know what he is pushing. On the other side of the coin is the shooter who knows he is getting 3,500 fps because that’s what it says the rifle should be getting in a book.


I can’t help but reflect on my experience with the velocities shown in reloading manuals.


In my gun cabinet stand eight rifles chambered for the .270. I reload for all of them, using the same dies, powder, primers and balance. That amounts to as close to the same as you can get. And yet there is a 200 fps difference from the slowest to the fastest.


Why?


Anything except actually measuring the bullet speed is simply guesswork. Back when I was a young shooter, chronographs were rare, and the few that could be found were expensive. Today’s hunter and shooter are lucky. There are a wide array of these instruments on the market for as low as $100.


What a chronograph does is measure the time it takes for the bullet to travel a certain distance. It then converts that to velocity.


Today’s electronics are wonderful things, and this little contraption contains a very fast clock.


There are two screens, which are faced skyward at a certain distance apart. The shooter then fires in such a manner that the bullet passes inches over the screens.


The bullet triggers the clock as it passes over the first screen and stops the clock when it goes over the second. The elapsed time is then converted into feet per second.


Most chronographs will also give an average speed of all shots fired, slowest, fastest and the standard deviation.


The problem with this system is when you are trying to set up on a crowded shooting range. Everyone has to quit shooting while the screens are being lined up.


Now, there is a new system on the market that works by fastening it to the muzzle of the rifle. It’s called the Magnetto Speed and can be attached without disturbing others shooting at adjacent benches.


It is also not affected by varying light conditions, unlike the screens, since it doesn’t require light to operate. The instrument creates a magnetic field, which is disturbed by the passing of the bullet, which it then converts to speed.


I have used one and the readings seem to jibe with the readings I have gotten with my Oehler and Chrony. I am far from an electronics genius, but more can be found by logging onto MagnettoSpeed.com.



George H. Block writes a Sunday Outdoors column for the Observer-Reporter.


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