2-4 MG strikes per AAA emplacment. 1-2 Mauser rounds per emplacment. 1 Hispano round, higher amount of explosive content allows for near misses so accuracy is not as important. Technically speaking, anway.
A8 with Mk 108 30mm might be comparable, but the lack of interupter switch makes aiming somewhat difficult. In raw power of total rounds the A8 is probably the highest, but that configuration and ground work are not very historic.
Only other plane that comes close to the ammunition potential of the 1C would be the Jug in overload condition (1700rds per bank) at 3400 total rounds. (most 20mm compared to a US .50 cal = 2 .50 rds, vs Hispano it's about 3 rds depending on type.) There is a certain need for accuracy though, because a near miss does not have the blast effect of cannon rounds.
So I don't really think that was an unecessary use of the 1C
Any plane can kill acks, it's just alot easier without mixed banks, a cannon round with a large high explosive content, with a flat trajectory, in a very rugged aircraft.
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33rd FW www.33rd.org