Hornady LEVERevolution ballisics question

[dig4gold]

The hornady sight ballistics table for the LEVERevolution 30-30 in 160gr shows the trajectory at the muzzle to be -1.70. (In another chart, it shows -1.5) I am assuming they are assuming I have a scope mounted. I have the Model 94 with Williams iron sights, no scope. So . . . how do I modify the 100 yd, 200 yd long range trajectories to accomodate my no-scope gun?
I can't just subtract 1.7" can I? Wouldn't it be logrythmic the farther the shot?

[salukipv1]

find a trajectory calculator...and put in .5" as the scope height or 0", though whatever the rifle sights height is would be most accurate...

I'd say .5" would be my guess.

[Ridge Runner]

go here, input your data use .5 for sight/scope height, or take the actual measurement
http://www.jbmballistics.com/cgi-bin/jbmtraj-5.1.cgi
RR

[dig4gold]

RR . . . that website link is awesome. I'm saving that!
FYI, I measured from the center of front sight to center of muzzle and it is .75". So the bullet is coming out of the muzzle .75" below front sight bead.
I would not have thought it was that much!