I have a rhetorical question for you, IC: What is your BC going to be used for, hunting or paper punching?
If it is primarily for hunting the most important shots are the first two out of a clean, cold barrel, or, as I do, the first ones out of a dirty, cold barrel. I fire off 3 or 4 rounds a few days before hunting season opens or before I head out to my hunting grounds and never clean the barrel bore until I collect or the season is over. I've used this proceedure since a old timer tought it to a first time 3030 user on his first hunt. The first two shots are the most important for hunting purposes. The first one should be placed to kill instantly, the second is for the twitch, either you or the animal, or when the first doesn't do the job.
I don't care what a 3 shot, 5 shot, 10 shot or more shot group looks like on a target other than they look very good and are good for whiskey talk. Ii the first one doesn't go where I aim the rest don't mean a thing.
When I am working up a load I always mark the first two rounds to see where they go in relation to the rest. They will also give indications of what the load is doing, what the rifle is doing and what you are doing with the trigger, your hold, conditions, if the scope has all the parallax dialed out and many other things only experience, reading and talking will teach.
Recoil isn't a problem for me, I don't have to creep up on it. I hold light recoiling target/varmint rifles just slightly less than heavy slappers, the same as I hold in the field. I don't let them "free recoil". I don't want the rifle to react differently on the bench or in the field. Get a good grip, pull it into the shoulder pocket and let her rip. I guarantee you won't be surprised if you forget and let a big bore get a head of steam, or creep up on the scope. How do I know...the college of Hard Knocks, and I have a PhD from that famous school.
The name of the game is consistency through out. A rifle is a system, consisting of all the components that go to make up the parts of the rifle, the parts of the ammo, everything surrounding the shooter AND the shooter.
If you just want to bang away at paper...all the above still applies. I'm not a target shooter but I follow many of the benchrest rules, because they apply. I want my hunting and varmint shooters to be bugholers if I can get them there, but, I would rather be hunting so as soon as I get "that load" worked up I head for the boonies, and if the rifle won't shoot when I grab hold of it, then it's useless for my puposes.
As far as how warm...if you can grab hold of the barrel and hold the weight of the rifle for say 30 seconds your OK. High heat will kill a barrel quicker than anything else. I fire 3 to 5 shots then let it cool while I walk to the target, check things out and walk back to the bench. It also depends on the caliber, the barrel size the outside temp etc. A rifle setting out in the August sun waiting for a shot, will get so hot you can't hold it. How do I know? Experience. I have burned out several HotRock caliber barrels before I even got a good loads worked up. Big cases, lots of powder and small holes down the middle. I've put over 4000 round through several 220 Swift barrels and they were still shooting 3/4" or less then I swapped the barrel or the whole gun. I just didn't shoot them until they turned red or cooked off a round in the chamber.
Mac covered the questions well so heed what he said.
Don't get too cranky when the targets get up in your face, just listen to what they say. Remember cases are not all equal. If you want the most out of your rifle and loads, buy 100 and seperate them by weight. 223 size, 1 gr spread. 308 size 1.5 gr spread, 30-06 2 gr and magnum 3 gr, or closer if you want. Buy one on of the neck wall checkers and seperate again, keeping the neck wall runout within 0.001". Remember if the neck is inconsistent so is the rest of the case body. Then turn the necks to within 1/2 a thou, 0.0005", use a carbide primer pocket uniformer on the primer pockets and a flash hole reamer to remove the burr on the inside of the primer pocket and trim to length. You should end up with about 85 cases all nice and closely matched. After all this is completed you will have eliminated about 90% of the problems with lousy groups. The rest is just finding the right seating, powder and bullet...Or...buy Norma cases to begin with and not have to go through all the above. It all depends on what accuracy you want and how far you are willing to go to get there. I know many people that are happy with keeping a couple of shots inside a pie plate at 100 yards. They always seem to get their meat and they spend a whole lot less than I do messin' about with my "scientific endeavors".
My BC shoots best with the bullets touching the lands and it also seems to like pressure around 45 to 50 KPSI. That puts a 300 gr at about 2500 f/s plus. Too fast for Hornady, but OK for Sierra bullets according to their published information. I posted some of my findings else where, you might do a search if you're interested.
I will be starting some test with Barnes X bullets soon and I will post that information as it develops.
One other bit of foam. I ran many test over the years on different aspects of reloading. One thing I always do when I get that one bugholer group is to refire the SAME cases without changing anything to see what happens. I guarantee you WON"T get another bugholer group, 9 times out of 10. Something always changes to mess with the group size. I used to have targets hanging all over my loading room walls of different caliber rifles with 5 - 10 shot groups all fired with the same 10 cases, within the time it took to fire, reload and fire again, 5 times. I just shook my head everytime I looked at them.
Enjoy NFG