First, use automotive wet-lap or whatever 1000-grit or finer sandpaper you can find to polish the feed lips. This will help some. You don't need to bend them, assuming feeding is otherwise reliable.
Then, try taking the coil spring out of the Magpul mag and use wire twist ties to fasten a couple of coils together, then reassemble the mag. This will reduce pressure in a full magazine.
Does this alleviate your issue? Is feeding improved, especially from a full mag?
If so, you have encountered the same issue as me. You can either leave the Magpul spring coils wired together or cut them. Unfortunately, the MDT mags have leaf springs which are not amenable to wiring - not enough room for the wire when the mag is fully loaded; I know because I tried.
I obtained a couple of MDT's longer, finer springs for their 12-round magazines; cutting a "fold" or two off the longer, finer spring reduced pressure and allowed easier feeding, but still not as slick as the Magpul (the full-length 12-round spring won't fit in a 10-round mag without cutting). It must be acknowledged that brass cartridge cases are going to drag more on the steel mags than on plastic. Polishing the lips helps.
@MDT_Josh, here's another report of stiff feeding with the standard 10-round mag spring. At a recent match, I spoke with several other shooters who are also experiencing overly stiff feeding from MDT 10-rounders, although everyone otherwise appreciates the solid build. However, in fairness to MDT, I must point out that, for me, feeding was too stiff in Magpul and Accurate mags as well as my MDT mags.
