Thanks guys. Really appreciate all the help.
....if I were to use the same loads that I already have, and just started playing with bullet seating, besides changing POI, will pressures start changing as well? Can I not just use the loads I have now, but just start tweaking the bullet depth to where the Rem likes it, or does changing seating start to change pressure's significantly? Sorry for all the questions. I don't completely understand when to use less/more powder or when you need to seat more/less after you have shot a few rounds. I know what to look for with pressure signs, but I honestly couldn't tell.... say if I had a huge group, if it was because of bullet seat or power charge... or both. Guess I'll just have to do what everyone else does.... shoot shoot shoot. Thanks
I will try to answer your questions as best I can, to keep you safe, and get your loads shooting properly for your rifle.
First and foremost, each rifle is a different creature from the next, it don't matter if they both came down the line one after the other. One will show pressures and preferences different from the other. This said, the load Kirby did for you were, knowing Kirby, tweaked to the particular rifle, he loaded them for. Just the particular way he is. Whether it was a seating depth, powder choice, or powder amount, he simply did not dump powder and seat bullets and call it good.
So that said, let's start from scratch and get your load to work for your new rifle.
First if this will be used as a repeater where your next rounds come from the magazine, this will determine your maximum OAL no matter what. I generally try to keep my rounds around .050" short of this measurement to ensure reliable feeding as some bullets will catch on the front lip of the magazine and lock up the action if they are right on the edge of fitting in the magazine. So once you determine what this length is for this rifle, you need to choose a powder that will give you a bit of flexibility above or below your desired end velocity. With the RUM this is usually with a 180 - 210 gr bullet found somewhere on a powder chart between 7828,and Retumbo. Now the charts are simply a guide as lots change from one to the next and can easily overlap from one powder to the next, in actual burn rate. With loading the RUM one thing your going to notice real quick is how fast you go through a one pound can of powder at the loads generally used. It's nice to use them to find a desired load, but when you settle on a particular powder, I highly suggest you get an eight pound jug. When you do, IF you lucky enough that they both came from the same LOT number you set, if not simply back off a grain or two and work back up till you hit your velocity or accuracy which ever comes first.
Once you decide on the powder you want to use, and your bullet your going to start with the START loads as every manual recommends. As noted with most of these powders you can creep up a grain at a time before hitting any big pressure jumps. There are several methods on how to optimize your work up to hit a load quickly, and you can use which ever you feel is best for you. Once I decide on which powder I want, and what bullet I want, I simply load up three rounds at a time moving up the powder weights as I go. This way I am only changing one thing at a time, and it reduces the variables, and a lot of head scratching.
As an example here is a work up I did for a Sako chambered in .243. I used the bullet I wanted to use and will continue to use, the brass was all new for each load, after setting the OAL to fit and function from the magazine, nothing was changed but the powder charge.
Using my Chrony I worked up until I hit the velocity which was equivalent to the factory load I used for comparison, and already knew shot extremely well. Once there with the load I simply adjusted the OAL a bit and got the rifle to shoot 3 shot groups well within 1/2" at 100yds. Knowing the stock needed a touch up to begin with I left things along until I can get it done. At that point I should have an excellent load for this particular rifle. I would not however, simply shoot this same load in a Winchester I also have, as it was not worked up for that rifle, and being different it could have a lasting effect on my personal well being.
If you have, or have access to a chronograph that will aid in hitting the velocity range your looking for. It might also show you a jump in pressure by the differences in velocity from one load to the next. If you get to high pressure with one powder before you get where you looking to be, switch to the next slower and start over. This is why I recommend a powder that has an overlap of the velocity your looking to hit, as it will generally be more accurate overall, and in more varied conditions your likely to encounter in the field, than one where you hit your desired velocity right on the edge of high pressure.
Once you hit the desired velocity, or if you see noted accuracy with one particular weight, you can either stop and use that load or then start playing with your seating depth. When I talk about noted accuracy, when you shooting your groups and they might all be hitting in a 1.5" group or less, then you add just a bit more powder, and it drops to half of that, you in the zone for that combination. However as was the case with my friends RUM, most anything he shot was great at 100yds, but at 300 half were spreading out. So it pays to recheck things.
If you have promising loads, and a chronograph, look for the ones with the lowest deviation. These will be the ones that you might want to consider playing with the seating depth even if they show a wider spread at further ranges. Just a .005" or so change can drop their group size easily in half. Don't be concerned with loading to the lands, my buds loads use Berger 185gr bullets, and are over .125" off and they shoot bug holes at 300yds.
Granted you might pick a powder, pick a seating depth, and toss it all together and get a shootable load, but to optimize the accuracy from your rifle you will need to experiment. As for the seating depth changing pressures, yes it will to a degree. However your generally much better off going in than going out and into the lands. When you choose a powder that isn't at the upper end of the pressure fo your load, you will hardly ever run into any issue with seating back in the case to a degree, depending on the bullet length. I generally look for powders which when the bullet is seated to depth, will come up and just kiss the bottom of the base, or only be slightly compressed. These are generally the ones that are on the middle to slower side of the burn rate scale for that particular cartridge, and usually give the best overall results.
I hope this helps you in some form or fashion. Working up loads can be a lot of trial and error, or you can cut the parameters down to help speed up the process of elimination. The bottom line is, that while some loads MIGHT BE, completely safe from one rifle to the next, you should NEVER simply throw them in a different firearm from the one they were developed for, and HOPE for the best. Like I read in another post somewhere, there simply isn't time to change your mind, and move out of the way once you pull the trigger, and the results can be pretty bad. Just consider, your looking at between 85 and 95 grains of powder, developing pressures of up to 65,000 PSI, only two to three inches from your face and hands.
Reloading is safe and exciting as long as you stick to the rules and precautions. When you venture outside these parameters however, your taking things into your own hands, sometimes literally.
Good luck and don't hesitate to ask first, there are no dumb questions, and everyone here started out learning at one time or another.