Just had a quick question about trying to zero.  The only range within reach this week has a max 15 yard range, so it'll have to do for the near future.

I just want to get out there and get it as close as possible to a 100 yard zero, so here's my thought process, please comment and correct my thinking.

Using factory loads, put info into trajectory calculator to zero at 100 yards.  based on assumed velocity (1000 fps muzzle v, 194 gr) and accuracy of the calculations (coef .48), it says it would impact at 15 yards a +1.68".  

so for the time being can I go to this range, aim at dead center and adjust scope until impact is 1.68" above dead center?  
I know if i zero at 15 then shoot at 100 it'd drop 10", so i'd rather not go that route.

thanks as always for the help.  

Your aim should be over the point of impact if I understand it correctly.  Look here:

http://www.ar15.com/forums/t_3_18/529846_UPDATED__Zero_Targets_Optimized_for_Red_Dot_Style_Optics__Aimpoint__EOTech__etc_____AR_15_and_AK_47.html

I'd agree with that for normal supersonic rounds, but at 1000 fps muzzle velocity, i'm already lobbing it to 100 yards.  it just doesn't cover that much ground so zero'd at 100yards crosses the sight plane within 5-10 yards.  

5.56 (~3100 fps) would cross sight plane between 40& 60 yards, so in that case yes you would be impacting below your sight at 15 yards.

no?

http://www.shooterscalculator.com/ballistic-trajectory-chart.php?t=cfb2a468