Did not see anyone mention this so ... every rifle is somewhat unique in what load it groups best with. The reasons are rather complex and no need to go into now. Exacting hand loaders like myself will fiddle with powders, loads, and bullet combinations hours on end looking for that "best" load.

Using factory loads, the method is similar. I would recommend is to buy (or bum 3 rounds from) 3-4 boxes of significantly different loads. Say for your 30.06 Spr. .... something "cheap" using a 150 gr., another maybe "premium" using 165 gr. , a third using 180 gr., and a different maker that uses one of these same bullet weights. The more different ones that you can try the more likely you are to find that one that matches your rifle best. But at $15-$60 a box that can get expensive in a hurry.

Go to the range ... make sure you are on paper good at 100 yards. I like to use a big piece of white "project" board for this phase of sighting in just to make sure I am "on" the paper !!! Then shoot 3 rounds aiming at a bulls eye centered in the target. Take your time between shots to let the barrel cool off. Shoot with the best form that you can. Don't sweat where the "group" hits. If it is way high and right of where you aimed for example, no big deal. What you are looking for at this point is finding the tightest group, no matter where that 3 shot group happens to hit.

With a pen, connect the 3 shot holes, forming a triangle. Now draw a line from on point to the center of the opposite side. This will form a 3-spokked "star". This is where the "average of that group is hitting. You can measure the distance from each bullet hole to the where these 3 lines cross. Average that distance and that is the measurement of how tight your group is. You should not settle for anything greater than an average of 2". If every ammo that you tried hit wider than this, try a few more. My experience is that you will be able to find ammo that will hit well inside 2".

Once you have found that best (tightest) group, then adjust your iron sights or scope for whatever "zero" you want. You probably will have to shoot a few more times to zero the rifle. If, as you say, your max range is around 100 yards, I'd zero it dead on at 100 yards.

Go back to where you bought the ammo and buy more of that same stuff that grouped great. Each box should have a "lot number" stamped on it. Stay with that lot if at all possible.

As far as bullet wieight for deer .... 150 gr. or heavier is plenty good enough.