Board Thread:General Discussion/@comment-26855942-20160223013316/@comment-4503347-20160223051402

All playable piston aircraft in Infinity so far have machine guns and 20mm cannons, and the Mustang only has .50 cal machine guns, so that is probably why it is not selected. As for the Hellcat, there is only one specific variant (F6F-5N night fighter) that carries a mixture of armament. The MiG-3 is equipped with two kinds of machine guns (7.62mm and 12.7mm).

But there are many other aircraft that carry machine guns and automatic cannons in WWII. Examples are, , , and. These are just the tip of an iceberg, but at the end it's up to Project Aces to decide whether to include more or not.