Ballistics and reticles and scopes, oh my! The MTC Mamba

Monday, June 2, 2014

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The folks who shoot air rifle field target are pretty serious about their accuracy. In the dozen or so years that I have been fooling around with adult precision air rifles, I have yet to meet a field target competitor who has his (or her) rifle set up to shoot faster than someplace in the low 900 feet per second range. I get the feeling that many of them (if they are not shooting in the slower, less powerful international class) have their rifles set up to shoot around 930 fps.

The reason for that is pretty simple: 1100 fps is the speed of sound at sea level. As your pellet approaches the speed of sound, it gets into a region of turbulence that screws up accuracy. If you ever saw the movie The Right Stuff, you might recall that scene in which Chuck Yeager breaks the sound barrier, and as his plane approaches it, he gets bounced around by massive turbulence. That turbulence region occurs whether you are approaching the sound barrier from below or are dropping down and through the sound barrier from a higher velocity. That’s why firearms varminters, who pop prairie dogs and woodchucks at long range, make it a point to keep their bullets well above the 1,100 fps from the muzzle of their rifle all the way to the target.

Okay, so what does that mean for you as an airgunner. Answer: you are going to be shooting slower that 1,000 fps and you are going to have to deal with the trajectory of your pellet. So, for example, if your air rifle is zeroed so that the pellet will land exactly where the crosshairs are pointed at 20 yards, at 55 yards, you are going to have to deal with the pellets dropping several inches below where the crosshairs meet.

Some shooters compensate for the pellet drop by spinning the elevation knob a predetermined numbers of clicks to make the shot fall where the crosshairs are pointed. The method that I prefer is to use a mil-dot scope which has multiple aiming points and then map where the shot falls at various ranges on a diagram of the mil-dot reticle. Below is a picture of the reticle map that Hans Apelles prepared for the Northeast Regional Field Target Championship a couple of years ago.

NE Championship and Pistol ft 010

The other factor that air rifle shooters must compensate for is the wind, and that’s where the MTC Mamba scope comes in. It has something called the Small Calibre Ballistic (SCB) reticle that not only has multiple aiming points like a mil-dot reticle, but it also has horizontal extensions on the lower aiming points that allow the shooter to more closely estimate how much to move the point of aim to compensate for the wind.

retSCBcombined

If you use a “windicator” – a feather or a bit of yarn hanging from the barrel of your rifle that indicates the strength of the wind – with some practice, you can correlate the movement of the windicator with how much you have to “stand off” with the SCB reticle. It’s a slick system that works very well.

Even better, scope delivers bright, clear views and is extremely solid built. It is the only scope that I am aware of that has metal flip-up scope covers. It feels like it is built to withstand years of rugged use without a whimper, and I would not hesitate to use one of these on my own field target rig.

Til next time, aim true and shoot straight.

–          Jock Elliott

2 Comments

  1. Chris says:

    Interesting scope. Are they connected with MTC? Looks similar to the scope they sell. Any ideas about a dealer?

    1. Jock Elliott says:

      Chris,

      They are connected with MTC and http://www.airgunsofarizona.com carries them.

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