You may just find that you have a rifle that shoots nice little .75 moa groups when they are all shot in the same session, but the cold bore shots combined make for a 2 or 3” group because poi is changing with temperatures or humidity or whatever.
That is very true. Most of my "long distance" shooting was at NRA Across the Course Highpower. Two hundred yards is not long range to those types who regularly shoot at animals at 800 to 1000 yards with a cold bore, but I sure saw the pattern move as the bore fouled. The higher the mileage barrel the more it walked until it fouled in. I also see this in Smallbore Prone. These matches start at 50 yards, and I can't remember a time when the first couple of shots out of a clean and oiled barrel were not out of the fouled group and tended to be erratic.
That being said, I wanted to find out how greased bullets and and cases affected groups given a cold bore.
I bedded this rifle before taking it to the range. I created a Devcon pillar before routing out a massive amount of wood and pouring in even more Devcon
free floated the barrel, the original barrel channel was touching almost all the way up
Using zero's established during a prior trip at CMP Talladega, perhaps this time
and greasing up my bullets, similar to this:
My first shot at 300 yards with a clean and oiled barrel:
The next nine shots
So the group was stable and the point of impact repeatable. This barrel may be non typical. It is from 1937 for one thing, and I believe it is a taper bore based on the fact that it feels tighter as a brush or patch is pushed down the tube. I do believe that being a tighter barrel is why this sporter rifle is exceptionally accurate.
Ever since a two time Bullseye National Champ said Colt revolver barrels were more accurate than S&W barrels, because they were tighter, I have been looking for evidence that choke barrels (or tight barrels) are inherently more accurate. I have an exceptionally accurate Benchmark .22lr choke barrel on an Anschutz, so I think there is something to this.
I am load testing when I go to CMP Talladega and so I don't start off with cold bore experiments at 300 yards, I will start at 200 and work my way out. And off the top of my head I don't remember what happened any other times I started off with the same load at distance.
Regards of previous zero's, you have to look at range conditions, observe the range flag direction, height, and mirage, and make best guesses as to wind drift, in elevation and windage. Most of the long range hunting stuff I read totally ignores the effect of wind on point of impact. Well, it is real. I remember the year in the pitts at Camp Perry and I was complaining my 223 bullets drifted 36 inches in the wind and I thought conditions were bad. A gnarly ex USMC shooter stumped over to my target and told me that when he won the 1000 yard Match, with his M14, he was aiming three targets over and had full right windage!
Based on the windage on a NM rear and the spacing between targets, his 308 bullets drifted 50 feet due to wind conditions! Horrible day to be out shooting!!
I can say when I shot 1000 yards, the first shot to the target was always a mystery. Given the same rifle, same loads, established zero's, at the same range, if my first shot at 1000 yards was in the black, that is the eight ring, I was a happy camper. Due to my experiences at long range target shooting I think the practice of "long range game hunting" is extremely unethical because the first shot is unlikely to hit a vital area of the animal, and thus increase suffering of the animal as it runs off and dies an agonizing death.