I'm an old newbie and I've been shooting exclusively indoors at 25 yards (except for one day not at a range) since I bought my Bushy M4. Weather has not allowed outdoor shooting on days available to shoot. Hope to get out this weekend.

However, my S.P.O.T. Red Dot (1x) is zeroed in at 25 yards, as you might expect, but how should I adjust at 100 yards or is it supposed to shoot the same at 100 as it does at 25?

Should I sight in all over again? Please help.

I don't have a magnified scope and will be shooting with irons and red dot. I will be shooting FedAE, WWB, Q3131, Q3131A all 55gr (of course), and XM193 -- which should I expect best results from? Will also bring a few 62gr Fed and XM855 green tips. I don't have anything heavier. Is it imperative I go buy a box of 68gr or 69gr Black Hills to ensure accuracy?

Oh, forgot to mention. I shot my new JP trigger for first time tonight and it was what I hoped it would be -- controllable. Except that the first shot fired shocked the shit out of me after having fired that sledgehammer Bushy stock trigger for about three months.

So using JBM's Trajectory Calculator and assuming a 16" carbine using full power 55gr loads (no wind, etc. etc.) and standard sight height:

Yards = POI (inches)
0 = -2.7
25 = 0.0
50 = 2.5
75 = 4.8
100 = 6.8
150 = 10.0
200 = 12.2
300 = 12.3

So, you'll be hitting 7" high at 100 yards.

As mentioned above, with your current zero you will be shooting close to 7" high at 100 yards.  If you want to adjust your sights for a 100 yard zero you need to bring your elevation adjustment down 6.5 minutes of angle.  Assuming your red dot sight has half minute of angle clicks, you need to adjust 13 clicks down for a 100 yard zero.