OK, this is not as simple question as you might think.  I've mounted a Leupold 6x at 2.6" over the bore, plus a piggy-back red dot at 3.8" over the bore.  See:

http://home.comcast.net/~jbures/wsb/media/124450/site1061.jpg

Now, I've choosen to sight my scope in at 100 yards.  Let's not get into that one.  I can switch to 200 easily.

However, I can't decide where to sight in the red dot.  Since it is so high above the bore, and will be used for <100 yards, I'm not sure where to sight it in.  Here's the trajectories based on a 50 yard zero, and a 100 yard zero:

http://home.comcast.net/~jbures/wsb/media/124450/site1063.jpg

If I sight in at 100 yards (red line), bullet impact will always be low below 100 yards.  If I sight in at 50 (giving a nice zero for a popular distance), then the path is even more divergent (see the yellow trace).

Opinions anyone?

BTT

Definitely DOT at 100.

As long as you have the common sense to account for holdover at anything inside of that range, you're good to go.

p.s.  Nic to see an occasional are with the scope mounted far enough forward for a decent cheek weld.

Quoted: Since it is so high above the bore, and will be used for <100 yards, I'm not sure where to sight it in.  Here's the trajectories based on a 50 yard zero, and a 100 yard zero:

That graph looks funny - did you set the tick marks so they would be at every 25 yards? (cause I don't see the yellow line crossing at the 50y mark.

Now you got to remember the 50y zero works with sights that are 2.6" off the bore - your sight is significantly higher.

With the 3.8" using M193 from a 16" barrel, a 50y zero produced a far zero of 300y with it rising as high as 4.6" (@ 200y).

However zeroing at 75 yards gives a nice 225y zero with the bullet rising no more than 1.3" off the point of aim (@150y)  So from 25y to about 260y the bullet is within 2.5" of the point of aim.  Of course under 25yards you have to compensate - but you have to do that no matter what zero you use.

100 isn't bad it's pretty close to the 75y trajectory.  Trading a bit of range for more precision at 200y and under.

Well, I'm leaning toward the 100 yard (maybe 75 yard).  The dot is for quick acquisition, not precise work.  If I need to pick up multiple targets quickly, I'll use the dot.  I'm probaly not worried about hitting low a few inches.  However, with the 50 yard zero, I'll have to worry about hitting low or high, depending on the distance.  That's a little more complicated.

Oh, yes, I was playing with the hash marks on the graph, and forgot to set them back.  The axes really start at -12.5 yards, with has marks every 25 yards.  There is no hash mark at 25, 50, 75, etc.

Notice the traces don't start at -12.5, but at zero yards.