That makes very good sense, Bullet bumper. I have owned a number of military rifles with fixed and they never failed to work.
I also owned one and shot a lot of M1 Garands and their "clips" never failed, as well as my issued M16 magazines never failed. My present issue M2 has fired a lot with no failures to feed.
An '03A3 I hunted with always worked, and well as a Mauser 7.65 Argentine I owned. I hunted with them a lot and without any failures.
I do agree, military grade fixed type magazines do have less chance of failure. A few of my sporting rifles have had detachable magazine problems.