Its the diffrence Sicario
20mm's are as how i imagined them to be. .50CAL's are not
.50CAL's had a longer effective range and way more punch on longer ranges. If a 20mm shell impacted near an armour plate, it did little damage. An AP-I round impacting at 400 meters did so with over 10 000 joules force, piercing trough an engine block, armour plate and into the cockpit of an ME109. Anything where it passed trough was showered with hot magnesium.