I've read that the magazine "safety" was one specification for guns to be entered in the French pistol trials, for which the BHP was originally designed. The theory was that armorers could just drop the magazine before putting the gun on the shelf and be certain that it was inert, rather than having to handle the gun, rack the slide, chase any rounds that ejected, etc., all of which were more dangerous (apparently, at least to the French) than storing a gun with a round in the chamber.
I shot BHPs in IDPA matches when I first began. One had had its mag disconnect removed before I bought it. But the new one I bought came with it. It's a little square plate that sticks out of the back of the trigger and is pushed in (forward) when a magazine is installed. If it is sticking out into the mag well, the trigger doesn't connect to the linkage with the sear, but if it's pushed in or missing, everything works fine. The "problem" is that the little plate slides up and down on the front of the magazine as the trigger is pulled. You can polish the little plate, and the front of the magazines where the plate slides, and even lubricate it, to smooth out the sliding surfaces. But the trigger action is still nicer (IMHO) when the device is removed, and the magazines always drop free when you punch the button. But IDPA rules required that all factory safety devices remain in place, and while I was never checked on it at our club's fairly informal matches, that was one of the reasons I switched to Glocks (before switching to my current K frame - just to keep things on topic for the forum in general

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Parabellum is from the ancient Latin phrase "Si vis pacem, para bellum." If you want peace, prepare for war. In "print" in that form since the 4th or 5th century, but probably traceable back at least as far as Plato's time. (Per Wikipedia.) It is, among other things, the motto of the Royal Navy.