STG 556, UTM

Originally published at Notes from the bunker…. You can comment here or there.

Went down to the GunPimp today to just say hi and see what was new. Surprisingly, they actually had something that got me a bit excited. I’d been reading about the new USA-made Steyr AUG clones but gun magazines always review stuff that we never actually get to see in the market place. Gunvaporware, I suppose. Well, this time they had two of these AUG-knockoffs…designated STG 556. One had the integral scope, which I heartily dislike, and the other had the now ubiquitous picatinny rail. Because the gun is a bullpup design theres a good portion of that barrel that’s actually stuffed way back into the receiver. The result is that a 16” barrel sticks out the front of the gun a lot less than 16”. The end product is an extremely short gun. This thing was in the rack next to an assortment of CAR-15’s and M4geries and this gun was easily about 4” shorter. Its pretty much right at the legal minimum overall length limit. This is not a true copy of the AUG…one major difference that left me scratching my head was an AR-style forward assist. The gun does retain some cool AUG features such as quick detachable barrel (which really doesn’t add much to compactness since the thing is so short already), ambidextrous ejection, and fold-up foregrip. It appears that while the mags will work in original Steyrs the reverse is not true so it’s a pretty proprietary mag. Obviously, I didn’t get to shoot the STG 556 but it handled very, very nicely. Its definitely a one-hand gun. I could see it being an extremely nice package for vehicle use, in tight confines, and other situations where a short barrel is useful. Price tag wasn’t cheap…$1700~ for a .223 is a bit much, but an original AUG will go for about twice that and you’d still be stuck with the kludgy integral Steyr optic. If I didn’t have a footlocker full of AR’s I might give one of these things a go, but at this stage in the game I am not adding another magazine into my logistics table. But, if you’ve got the money, it might make a fun addition to the gun collection and turn out to be a very nice shooter. If nothing else its not another M4-knockoff like you see everyone at the range with these days.

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I was cleaning my rifle today and, as I sometimes do, I took the opportunity to play with the mil-reticle ranging system. Theres a building a few blocks away with a roof access door that I can see from my shop. Well, I measured my own door which turned out to be an even 36” across (1 yard, right?). I figure the door on the building I was looking at was probably the same width. I ranged it through my scope at about 3 mils. So, the formula is [size of object in yards] x 1000 and then divide that by mils to get range. So: (1yardx1000)/3mils=333.33 yards. Now, how to check that distance. This is where it gets interesting. I use my GPS to take the coordinates of where I was and the coordinates of where I was glassing. Then, using a little Pythagorean math come up with the distance. Here’s how:

(a^2) + (b^2) = (c^2) is the formula

Heres the short version:

Take your position in UTM coords. You get two numbers, your x and y axis. Take the coords of your target, also in an x,y format.

Example: your location is xxx,yyy your target is aaa,bbb.

Subtract xxx from aaa, call that number N

Subtract yyy from zzz, call that number P

If the numbers wind up being negative, ignore the negative sign. We just want the difference between the two numbers.(Meaning if you get –1542 just call it 1542 [Number freaks will remind me that the negative is irrelevant since squaring a negative will always result in a positive])

Now the easy part: (N^2) + (P^2) = LASTNUMBER

Find the square root of LASTNUMBER and that’s your distance in meters.

So, I entered the coords of my shop (where I was cleaning the rifle) and the coords of the building I was scoping and wrote a quick spreadsheet to do the calculations. Result? 348 yards. Off by about 45 feet (15 yards). I attribute that to the difficulty of holding the rifle steady and the crosshairs dancing, also the door is located at the center of the buildings flat roof, not at the edge of the building and the edge of the building is where I stood to get the coordinates…so theres a bit of offset in there.

My point here, however, is that if you use the long/lat coordinate system on your GPS its a lot harder to tell the actual distance between two points. UTM is much, much easier to do math with..unless you can tell me what the difference in miles/yards is between 2 minutes and 32.879 seconds in a hurry.

Its an extremely easy bit of work to come up with a fast spreadsheet to cover the math.

One thought on “STG 556, UTM

  1. Good UTM reminder.

    I haven’t seen the new AUG, but I did have the opportunity to shoot one of the originals some time back. I really liked it, but didn’t choose to buy one (they were considerably cheaper back then) because of the built in crappy optics more than anything else. But the length, the accuracy and the easy handling were big plusses.

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