A couple days ago I was talking with a guy well versed in Tikkas and the mag issue.
The issue seems to stem from the feed lip angle. From what I see, the 223 is just the right size in stagger stack configuration, the top round is pushed up against the feed lip and the next round down create a force nearly perpendicular to the bottom lip of the feed rail the case is touching.
white line is general load angle against feed lip through top two cases.
I messed with a couple other ideas to create a different angle to deflect the top cartridge enough it couldn't hang up.
As is usually the case, the simplest solution has worked the best.
Right at the forward end of the feed lip, there is a rib that runs down inside the mag. I scuffed the feed lip and top ⅛" of the rib and put a drop of super glue there to "bridge" the angle change.
In effect, this shallows the angle by about 15 degrees so the top cartridge can't get caught. By simply forcing the shoulder into the center of the mag, the body follows not having enough surface area to get stuck.
So far it works on 4 and 6 rnd mags, mag after mag after mag. I've not had a single fail to feed after about an hour of just load mags, cycle through gun on the bench.
As far as longevity, I can see it being fairly long term as the only time anything touches the glue is as the cartridge comes up and moves to the center feed position. As the cartridge is stripped from the mag, it only touches the very corners of the feed lips. There is never really any load or abrasion on the glue.