I have limited experience with factory loads. I have mostly bought all of my components and rolled them myself. The few factory loads I have shot, seemed fairly hot. Start with fresh cases, full length sized once fired cases from other guns or neck sized cases fired in your same gun. Pick a likely bullet or two for your application. Now pick an appropriate powder or two from your reloading books. Based on the case size, powder type, availability, pressure of cartridge, etc decide on a primer. Find the OAL of your case based on your bullet selection and the chamber to determine where the bullet will touch the lands. Then depending on your application decide how far from the lands to seat your bullet. For a big game, cambering reliability dictates that your bullet have some jump to the lands. For bench rest work, you may decide to start in the lands. Once you decide where to seat your bullet, we start looking at powder weights. When you work up a load for you gun, start with the minimums recommended. Then depending on the case capacity, make minimal jumps in powder weight. For a 22 Hornet make .1 or .2 grain jumps. For a 243, .5 grain jumps will work. Start firing your loads in the order you loaded them from lightest powder weight to the heaviest. Note group sizes and when they have shrunk to their smallest size with out increasing to the next weight in powder, you have found your load. Do not exceed recommended powder charges under any circumstances. If you can not find any thing that satisfies your accuracy goal, then start over with a different powder, bullet or primer. If you start over with any component, start low and work your way up again. Once you find an accurate load, then you can experiment with OAL to see if that helps you or hurts you. If you have tried several powder/bullet combinations and can not find anything reasonable accuracy wise, you may have a problem with bedding, bad crown, loose mounts, in other words, some thing wrong with the gun. Like I stated above, I do not worry about top velocity, because I have found that the few fps difference does not really make that much difference, not as much as you might think. 150 fps difference will probably only mean less than 50 yards in your over all point blank range. With a 223 maybe 260 yards vs 300 yards, big deal. I have covered a whole lot of ground here, so there maybe some thing that you are not clear on, if so ask, i will try to answer the best I can.
As far as case annealing Hornady makes a kit for annealing cases, that I found very easy to use. It has three sizes of case "spinners", a bottle of heat sensitive liquid and instructions. Annealing is for the case mouth and shoulder area only. Do not think you can stretch primer pockets and shrink them back down. It will not help with head separations, both can be caused by over pressure situations. If you are running high pressures, you will be enlarging primer pockets and stretching the case so much that annealing will not be needed, you will ruin the case before any annealing will be needed. If you continually run high pressures, you will not need to anneal. There are lots of folks that do this, they never anneal, because there is no need for it. I anneal some where around 8 loadings or so, depending on what gun it is and how much the brass is being worked in the neck/shoulder area.
Some guys like to brag about how fast they can push such and such bullet. I would rather brag about group sizes. The two do not go hand in hand, some times they do, but not always. If I have to run on the ragged edge to get out the accuracy, I switch loads, I just do not like to run that high, you not only shorten the case life considerable, you run the risk of damage to you gun or worse your self. I have been down that road of getting as much as possible out of a cartridge. I have had blown primers, primers that fell out of the pockets, split case necks, the whole gamete. I have found that I did not gain as much as I thought, and I never knew how it was going to act. 1 shot would be OK, then a blown primer the next. I just never knew what to expect when riding that fine line. I found this out shooting a 222 Remington for years. I ended up switching to a bullet that would blow up way down to 2000 fps. I was able to hit black birds out to 250 yards. It did every thing I needed and I was running in the 2900 fps area with 50 grain bullets. If you know of someone that has been reloading for a long time and really enjoys the hobby, I think you find that they are not running on the ragged edge either. It comes with experience, you just find out that that few extra fps is not worth the problems it causes. If you really need to get more distance (velocity) out of your gun, then you really need to think about getting another gun that will do what you want. If what you want is out of reason for the biggest baddest cartridge you can get, then you are expecting too much out any gun. Be reasonable. Be safe. just my 2 cents. Good Luck and Good Shooting