I have a Rem 700 LA mag in 338 RUM and i want to get a longer box so I can seat the 300 grain pills a little closer to the lands without having to single shot my rifle. I would like a 5 round maybe?, magazine fed box. I am not sure where to go from here I've seen a few different variations of what I'm looking for i just want to spend the money on the right one the first time, like if one has an advantage over the other maybe a little more length. I don't know school me on this guys! Any and all advice will be greatly appreciated!