1. Material problem of barrel. The level of iron and steel smelting in western countries in Europe and America is higher than that in Russia, so the heat dissipation of barrel is relatively better.

2. The problem of firing rate. 127 firing rate is 20 rounds/min, AK 130 firing rate is 70 rounds/min (single tube is 35 rounds/min), the firing rate is fast, the bore wears quickly, and the calorific value is high, so auxiliary cooling and heat dissipation are needed.

3. The caliber is not an absolute problem. Take France's 100mm compact naval gun as an example, with a firing rate of 90 rounds per minute and a cooling system.

4. For another example, the Italian Otto Melella's 127mm naval gun fired at a rate of 35 rounds per minute, but he used a liquid-cooled barrel (the inside of the barrel was hollowed out and filled with coolant), so there was no leakage.

5. Different structures lead to different weights. MK45 naval gun is only 20 tons, the liquid cooling weight of Italian 127 gun position is 40 tons, and the self-weight of AK 130 is more than 90 tons.

7. The weight and firing rate of ground antiaircraft guns and ship-borne antiaircraft guns are also different. The maximum firing rate of the Army's dual 35mm antiaircraft gun is 550 rounds per minute, and it is cooled by air. The 76A naval gun is 800 rounds per minute, with high firing rate and heavy weight, which is not suitable for vehicle.