Boats - We sight in with only 5 round shot groups to insure accuracy. Normal zero drill for us at 100 or 200 meters is to fire a single shot after bore sighting to insure we hit paper and can record a sight adjustment. We will then make a half change, as an example, if the estimate si that we move the need 6 minutes of angle (moa) adjustment, we will do only three and fire an other single shot. From that second shot we will make another required adjustment and then shoot a three round group to see if we are in the ball park. A final adjustment and we fire a confirmation 5 round group. All other groups will be 5 round groups after that. You get a better feel for the mean point of impact from 5 rounds then you do with three.
Our ammo comes from the Army and we do not have to be stingy as if we have bought our own. Plus our guys will try hard to make some bad guys head swell up and spew brains out the back.
Cold weather has effects on the bullet as the air is slightly denser and thus will cause the bullet to strike slightly lower. The effect on the shooter is personal and varies fomr shooter to shooter but a disciplined shooter should not really show any effects at all. Have a buddy who shoots at the Yakima in Washington state in the winter all the time. (personnally I think he is a bit touched but then again he retired as a SF Major so what can I say?
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Hope I answered your questions, if not then ask away and I will do what I can to answer them. Just got off the range with a the students, they were shooting 500 to 800 meters today and seemed to be doing well. But you know Army guys, give them guns and bullets and they are happy.
