28 December 2014


There are occasionally times when I'm thankful I was awake in a couple of my math classes.

Last night I asked, "is my rear sight centered?"

No.  It was not.  From the side of the frame to the base of the rear sight on the left side of the gun it measured 0.109" and from the right side it measured 0.083".

I could have moved the sight to the left and measured both sides until they matched, but I can haz maths!

The distance to center is one half the difference of the measurements.

(0.109" - 0.083") / 2 = 0.013"

The sight mover uses a 3/8-16 UNC thread pusher.  So every complete rotation of the screw is 1/16" of an inch or 0.0625".

0.0625 / 0.013 is 0.208 which means about 1/5 of a turn to move the sight where I needed it.

And you thought I wasn't listening, didn't you Mr Smalling?


  1. Maths can be quite useful. I remember playing one of those obnoxious browser strategy games for a while, and I pretty much revamped my alliances entire army simply by running some basic calculations. Price per point of damage, health, etc. on various units to determine optimum army/navy compositions, and we all proceeded to wreck faces. Most games with guns having certain amounts of damage and ammo, multiply to get max damage output. Sometimes it'll surprise you which gun is the best, that built me a LOT of "Excellent" and "Superb" rating Armored Cores.

    And of course, tabletop gaming. When you roll like you're cursed, you have to do everything you can to stack the deck a bit.

  2. Okay, but what did it do to your point of aim?

    That's why you're supposed to remember your aiming dope so you can reset a new M-16.

    1. It was actually to put the replacement sigh in the same place as the original.

      I stopped attempting the "dope" method of taking an AR from mechanical zero to personal zero about the third time I tried it and it didn't work at all. If the point of impact was identical on all ARs set at mechanical zero, it'd work; but...

    2. Okay.
      It won't get you zeroe'd, but it'll get you close.

    3. It may be that military guns DO hit closer to the same point as each other at mechanical zero. That would make the dope method perfectly cromulent.

    4. *As it dawns on me that Mc Thag was talking about civilian variants*.... Kurt went.."OH, yeah they wouldn't"

      But he's right and I'm right ----depending on what you look at.

    5. Ayup! As a tanker I got taught the dope method, then couldn't apply it to any issue weapon since we trained on the M16A1 in basic and got M16A2 in my line unit.

      I was excited about giving it a shot later, alas...


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