Nate? I have one of the ramline mags, I can put eighteen in the mag, and one in the chamber. It does fit flush, no visible difference, and mine has never failed to function. If you can get them, do it, and enjoy. But do not pay too much, factory mags can be found cheap, and fifteen rounds are a lot.
The difference is that they have a "ribbon spring"? The spring is a strap that rolls to the bottom of the mag, instead of an accordion spring that needs space at the bottom. With an empty mag, if you remove the base plate it is empty all the way to the follower, at the top. If you wish, I will try to get some pics, so you can see it.