If I've got a quad 50 I don't want to be rude up close I'd prefer to be rude at a distance where the favor is more difficult to return.
The -10° leaves too much ground unswept. If sappers get under the guns you better hope there are some dog faces working your side of the street.
With experience that usually was not a problem. In the 90th ID after the experience of A Battery with the 357th Infantry in TF Weaver, usually one of the M17A1 platoons of the 537th AAA AW Bn was attached to the lead infantry battalion. Depending, they would remain under the battalion commanders control or two or all four would follow the leading company's rifle platoons. It was found it was the best way to quickly balance the inequality in automatic weapons firepower and mobility...four .50 on a mobile, lightly armored mount often beat a single MG42. Defensively, the SP Platoon was often deployed with the rest of the .50 M2 water-cooled on tripod mount M2...eight of them, and sometimes along with the eight 40mm in the battery (although the 40mm typically remained with the DS artillery battalion), integrated into the infantry's fire plan.
That's very interesting. It mirrors the German experience in learning to use light AA like the 20mm (mounted or not) against ground targets. That's a real stand-off weapon if you have a convenient hill at hand. You'd need tanks or artillery to neutralize it. .
If I remember correctly, there was an animal called an M42 Duster, armed with twin 40mm Bofors that was used in Vietnam. However, the nose fuses on the 40mm projectiles apparently were quite sensitive and it had a hard time penetrating thick brush. (Article in Vietnam Magazine, quoted by wiki)
The 40 MM AA guns on USN ships during the kikusui attacks had fuzes that were like that. The idea was to detonate on contact with the aluminum frame of the aircraft. The IJN's 20 MM ammo was generally set up the same way, unless they knew they were going after a "hard" target. The super-quick fuzes made attacks on the fuel storage tanks at Pearl irrelevant as they didn't punch holds in the .5" (12mm) to 1.5" (37mm-ish) steel used in construction of the tanks. .