Large? Not as large as the A10’s 30mm round and the A-10 carries over 1,000 of those.
For this Russian jet the number of rounds is awfully inadequate. They likely expect a one pass haul a$$ worth of gun engagement as that box car can’t turn worth a darn to survive a gunfight.
Most fighters carry about that much, look into F-18, F-16, F-15 etc, the A-10 is in a different category. They are usually 25mm, and big enough, not much smaller than 30mm.