I thought I would post this because I don't see very many M14's around that aren't scoped. It and the M1 have the greatest irons ever put on a rifle!!
* EDIT* Old guys, I know you cant see anymore

did not mean to pick on you.
I know not everybody has been in the service or really had the instruction to become lethal with irons so here it is. Get yourself a nice Garand rear sight and have at er.
This is the base formula for these standard issue rifle sights (M14/Garand).
1 click changes the impact of the bullet approx 1" @ 100m/y
M14 sight is graduated in meters M1 sight in yards.
Elevation adjustment range: 0-72 clicks
Windage adjustment range: 16 clicks L or R of center index.
With your rear sight windage index lined up in the center, adjust your front sight side to side until you are shooting exactly center line. This is best done at 25m from a rest at a piece of 1" wide vertical tape.
For Bullseye zero: Zero @ 100m (usually 6-8 clicks up from bottom).
Elevation: Once you are in the bull @ 100m with a 6 o'clock hold, dial the elevation all the way down while carefully counting the number of clicks. REMEMBER THIS NUMBER IT IS YOUR ZERO! Dial the elevation back up, again counting the clicks. Now loosen your elev knob pinion screw while firmly holding the aperture in place and set the dial to the 100m mark. Tighten the screw and fire on target to confirm zero. All of your sight adjustments will now work off this specific number of clicks which is your zero. Remember that every rifle will be slightly different.
Hungry here: I like to tighten the (single hand tight , not 2 hands...) elevation pinion screw, then bottom out your aperture, tighten up more. Crank up your aperture all the way to the top, then tighten up AGAIN!
For battle zero: Zero @ 250m (usually 12-13 clicks up from bottom)
Then shoot point of aim. Allows for engagement of man sized targets from 0-400m by aiming center mass. This is of course not for precision shooting.
Using the sight working off your bullseye zero.
Range 200: 1 click = 2"
Range 300: 1 click = 3"
Range 400: 1 click = 4"
Range 500: 1 click = 5"
Range 600: 1 click = 6"
and so on.
M14 issue rifle 22" barrel 26" sight radius.
Range 200: Your shot hits 8" low. Raise elevation 4 clicks, fire.
Range 500: Your shot hits 15" low. Raise elevation 3 clicks, fire.
Range 600: Your shot hits a foot high. Lower elevation 2 clicks, fire.
Range 300: Your shot hits 9" high. Do the math

Fire!
You always round up your clicks. Range 400: Your shot hits 10" high. You will lower elevation 3 clicks not 2.
Once you've mastered the grade 4 math calculations you can hit the range.
Target 500m. You turn your elevation knob to the 500m mark to engage a target at that distance and fire a spotting round.
Your spotter tells you it missed, 20" low, correction 4 clicks elevation, fire.
Once you become one with your rifle you will know the number of comeups (clicks) from zero required to make hits at certain distances. You can put them on a small laminated card and tape it to the stock. As long as you have that info you can simply estimate range, dial in and actually make a first round hit on target with that particular rifle.
Example: Target 400m, +16, fire.
Always reset your rifle back to its zero (and the windage back to center) when finished. If you cant remember write it on your rifle stock. Once you get good at this you will be able to make hits at varying distances very quickly.
Hungry here: At 100yds/meters, use every attempt to mechanically center your rear sight base with respect to the vernier scale (I like Whiteout or model paint) that is easier to read. Then zero for windage by (allen key to loosen) tweaking the front sight in the opposite direction you want the MPI or bullet strike to move into. This is for very serious competition or for you perfection addicts! 
LOL
Windage knob Corrections
Formula is the same: 1 click L or R @ 100m shifts bullet impact approx 1"
@200m - 1 click = 2"
@300m - 1 click = 3"
and so on.
Correcting for Wind G.I. formula
Range X Windspeed divided by 10 = Number of clicks.
Winds coming from
12 and
6 o'clock have little effect.
No correction.
Winds coming from
1,5,7,11 o' clock have a slight effect.
Half correction.
Winds coming from
2,3,4, and
8,9,10 o'clock have greatest effect.
Full correction.
Range 500:
Wind: 6 mph
Direction: 9 o'clock
5X6 = 30 div 10 = 3
Answer: 3 clicks, full correction, left windage
If it was a 1 o'clock wind it would be a half correction (1.5 clicks) On a standard GI sight that wont go so remember, round up your clicks.
It would be 2 clicks, right windage.
Test
Range 400, 5 o'clock wind 18mph. Your first shot is a foot low and to the left of the target. How would you adjust your sights to try to make a hit with the next shot?
National match sights
They are 1/2 MOA per click GI are 1 MOA per click. Just X everything by 2.
Hungry if I missed anything please add it.
Hungry here: Pretty darn good, I must say. I'm still looking!