i never said i had any problems loading mags, i'm just saying it takes more force to compress the spring the height of a cartridge on the last round than it does on the first. true?
Yes, which is what I've been saying all along! But it's a linear relationship, and depends solely on the displacement of the spring. Each cartridge you put in that magazine will be a little bit harder to push down than the one before it. So yes, the natural conclusion is that the last one will be harder than the first.