<Snipped quote by Kimiyosis>
Rin tops Shirou in the Captain Obvious category, like everything else.
Also, how does artillery work in space? It's not like there's gravity or anything so the 150 would pretty much be a direct fire weapon, wouldn't it?
Oh, and a friend of mine pointed out that 20-30mm cannons are actually fairly weak. They're early WW2 gun calibers and couldn't even beat a tank's armor in this day and age, much less in a futuristic setting. A better "scaling" of calibre to size would probably be along the lines of 120mm guns on modern armour for "rifle" calibers.
Yes, the artillery cannons would be a reduced to a direct fire weapon while in space.
Also, your friend is right and wrong. 20mm and 30mm
are WW2 gun calibers, but they are also modern day calibers too, such as the 25mm and 30mm autocannons used on American IFVs such as the Bradley. There are also many different types of 20 and 30mm shells as seen in this image- the WW2 shells are likely not the exact same as its modern day variants,
Also, keep in mind that a MAS is primarily an 'evolution' of Aerospace fighters, not tanks. Current standard calibers for aircraft cannons are 20 and 30mm- both of which are designed to penetrate armor, which they do rather well. Keep in mind that weapons in this time are also magnetic/mass driven weapons, not propellant driven weapons. Ballistic weapons in this age have begun trading mass for acceleration, as well as more advanced metallurgic and explosive technologies that have no doubt been developed by this point in time.
A 120mm round would be acceptable for a heavy/long range rifle weapon, not a rapid fire autocannon.