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The Speed Read

The Speed Read
We Test An Acoustic, Electro-Magnetic
And Optical Chronograph.
Each Proved Versatile And Accurate.

I have owned and used several Oehler chronographs, presently using the 35P. The unit is accurate and a marvel of electronics. Three leads run back to the receiver, which prints out each shot and records the high, low, spread, and average of the group of shots. It also calculates and records the standard deviation. It works well and is very accurate.

I have tested it against values published in various papers for barrel length and at standard conditions where I live on the coast. I use the results to input data into software programs that output the trajectory path, and using it in competition, my comeups are right on. For example, if the chrono gave false readings, say 150 fps higher than it really was, I would hit low at long range and be frustrated as to why.

The SuperChrono set up on Jake’s tripod. The readout on the unit is the average velocity of that string of shots from a .308 Winchester. The arrows allow you to step through the velocity of each individual shot. The buttons on the right are used to give either fps or mps. The buttons on the bottom give average of the group, reset, and turn the unit off and on. The SuperChrono will record 99 shots at a rate of 600 rounds per minute with no missed shots.

Acoustic Chronograph

But the Oehler is a bit bulky, and I have wished for a very small, accurate chronograph I could take anywhere in the country when competing or hunting. It appears that I have found it in the SuperChrono from Steinert Sensing Systems. My shooting range is located at 60 feet elevation. The temperature runs about 75 degrees F when I shoot early in the morning, and the pressure is about 29.53—very close to standard conditions. I take the data and enter it in a ballistic software program that outputs the trajectory path. It gives me comeups in either MOA or Mils, and it tells me where each reticle hashmark will hit. Great!

But then I travel from the coast to 8,000 to 11,000 feet to either compete or hunt. The pressure is much less, the temperature different, etc. I have to guess the velocity change and trajectory path. I would have better results if I could chronograph my bullets in those conditions and then print out a new comeup table for density/altitude. But the chronographs I presently use, and will continue using, are too bulky to haul with me to the boondocks. Enter the Steinert SuperChrono Acoustic Chronograph.

The SuperChrono weighs only 10 ounces and is just 10 inches long. It has one 1/4×20-inch mounting thread, which attaches to most tripods. It will give accurate readings in any lighting conditions, rain, or snow and works from -4 to 158 degrees F. It takes readings near the muzzle, but it can also be put between or near the target, which could be used to calculate the ballistic coefficient.

The unit was developed and is sold by Steinert Sensing Systems located in Oslo, Norway. Unlike optical chronographs, the SuperChrono uses acoustics. It operates by sensing shockwaves passing over sensor 1 and then over sensor 2. It works as long as the bullet is traveling at supersonic speed.

Simply aligning the unit along the barrel/target line is not the correct way to use it. The SuperChrono has sights, which are used to sight the unit at the target. I lined the unit along the barrel/target line, but then I used the sights, much like aiming a pistol at a target, as well. The unit registered the velocities I am used to seeing.

Paying attention to the instructions is not my strong suite, but it pays in this instance. The instructions include a table that tells the user the best heights to mount the unit below the barrel/target line if shooting from distances of 25 to 400 yards for various velocities. In my case, the .308 should be in the vicinity of 2,700 fps. The table suggests mounting the unit 8 inches below the barrel/target line for that distance and velocity.

If the unit is set up by these parameters, it is very accurate. In the field, a hunting trip in the Rocky Mountains, or whatever, it might be unlikely I would have a bench from which to shoot. It so happens that I have a tripod that measures 7 inches high but can be set to as low as 4 inches. In the prone position and using that bipod or a pack, I could set the unit up correctly. Since most of my hunting rifles have velocity ranges of 3,000 to 3,300 fps, the unit should be 7 inches below the barrel/target line, not hard to achieve in the field for the advertised 99-percent accurate velocity readings.

It is possible to shoot over the SuperChrono in the prone position using a small tripod. Jake hasn’t tried placing it on a rock, the ground, or a can yet, but it should work fine.

Testing

The advertising says the unit gives readings that are 99- to 99.5-percent accurate. The next logical step was to test the velocities recorded against the Oehler.

I used both the Oehler M33 and the 35P to test the accuracy of the SuperChrono. I set the Oehlers up so the distance between the sky screens was about 10 feet in front of the muzzle of the rifle. I set the SuperChrono up just beyond that, which was about 14 feet in front of the muzzle. There is a 1.05 fps velocity drop per foot. So if the muzzle velocity of a .308 was a true 2,700 fps, the Oehler at 10 feet would register about 2,690, and the SuperChrono at 14 feet would register near 2,685 fps. That worked!

I may have made this sound more difficult than it is. There are just four things that must be done to get accurate results: 1. Line the rifle, the target, and the SuperChrono up so they are on a parallel line. 2. Use the sights on the SuperChrono to aim the unit at the target. 3. Move the unit below the barrel/target line for the velocity range you believe the cartridge will give you, for example, 8 inches for a muzzle velocity of 2,700 fps. (The velocity ranges are given in the instructions.) 4. Move the unit away from the barrel so the distance from the muzzle to the back end of the unit is greater than the height from the top of the unit to the gun.
By Jacob Gottfredson

SuperChrono
Maker: Steinert Sensing System AS
Professor Dahls Gate 3
O355 Oslo, Norway
www.steinertsensing.com

Importer: Rifles Only
188 South F.M. 772
Kingsville, TX 78363
(361) 522-4165
www.gunsmagazine.com/rifles-only
Sensor Type: Ultrasound microphones
Detection: 10″ to any distance downrange
Velocity Range: 1,234 to 5,632 fps
Size: 1.8″x4.7″x10.2″
Weight: 10 ounces
Capacity: 99 shots
Operating Temperature: -4 to 158 F
Price: $349

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