Hello. I've spent a few hours searching and found most of the answers, but still have questions. I have a factory 300 RUM Sendero ll. I just started reloading and I am completely lost on things like, bumping the shoulder, only half neck size, only partial full length resize, etc.... It seems very easy for me to just full length, trim, etc... and of course checking wall thickness, reaming, etc.. But whether or not to full resize or neck really confuses me. I realize its harder on the brass to always full length, but it seems there is a lot less I have to check and worry about. Besides, what is a bag of brass every year or two. No biggy. If I had a Shilion barrel, McMillian stock, trigger, etc.... well, a custom rifle, then I would for sure be using fire formed brass and doing everything I could to gain the most accuracy as possible, but........ ......is there "that" big of a difference in a "factory" rifle to go ahead and only neck size and using fire formed cases over using full resized brass? I enjoy shooting out to 7&800 yards, but only on targets. I'm not near good enough or confident enough to take a shot at an animal at that range, but am out to 500 yards. If I were to shoot at extreme long range, then I would be doing everything possible with my brass to gain the most accuracy as possible. I have lots of fired brass and would like to use it, but I'm unsure on what to look for in reloading it beside trimming it. I don't know what I'm reallying looking at when looking at the shoulder, the neck wall thickness, etc. How many reloads can I load before worrying about the shoulder moving forward, ejection broblems, wall thickness? I would like to use the fired brass, but have no real knowledge on it. I've preped all the brass as far as weighing it all, deburring, primer pocket uniformidy, etc... If there is not that big of a difference in formed brass and full lenghth, then I'll full resize. If there is a thread somewhere on here and someone can point me in the right direction, thanks. Also, my RUM has a very generous throat. It would be a single shot if I wanted it .010 off the lands. So, another question, to get the most accuracy out of bullet depth, how far under over all magazine length do you seat your bullets to where there are no problems with magazine feed issues? Any help would be great. I need to load tonight to sight in tomorrow to finish off the last 3 days of season. Thanks for the help.