Though from this, assuming the figure is to scale. 40x180 isn't actually noticeably larger than 30x173, while sure the 30mm necks down but that doesn't really matter in a ammo chain.Possible. If sophisticated fuses are involved, 20-30 mm rounds really have low volumes available for the explosives. The illustration is below. The 30 mm does have an advantage though. Magazine depth... The 40 mm cartridges are much larger. Telescoping solves some of problem but may not be enough. I would not be surprised if both remain in service.
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