Yeah, some idiots do it.. Most don't know why..
The idea was to use recoil as lateral (sideways) spread of multiple rounds, preferably a full clip..
Preferred target, .... a crowd, or group of people..
There is no accuracy involved, it is basically a "shotgun" effect, and often used from a moving vehicle.
( say, "drive by shooting"..
True enough, with a few added details. Note that the practice goes clear back to the days of flintlocks, when in light drizzle, some shooters would rotate the lock side of their pistol to the bottom for protection from the downcoming elements.
But in more recent times several other rationales can come into play: firing so that your brass is deposited straight down can prevent throwing fired brass neneath a teammate's feet, a really good idea if the one to your side happens to be the one tasked with tossing in grenades or flashbangs and already has the pins out. Or has a flamethrower strapped on his back...
Likewise, the use of gas masks sometimes requires that the operator's rifle be rotated 90º for use so encumbered, and some also apply this to the handgun. The Israelis prefer a *Condition Three* handgun carry with an empty chamber, and teach a *slingshot* cocking method of quickly working the slide with the gun rotated 90º to utilize the maximum strength in the wrist muscles. In all such circumstances, however, the gun should be so positioned as to dump the brass downward, not up.
The use of the full-auto Mauser broomhandle M1932 *Schnellfeuer* turned sideways was indeed a way to keep those guns and their Spanish copies thereof from climbing over a target, and walking tone sideways against multiple hostiles was indeed then acceptable. Likewise the full-auto Star Model D and MD and other fullauto handguns can be more practical so employed with an initial full-magazine dump as an attention getter, followed by a reload and short bursts into individual targets. See following for details.
