Here's an inside look at a Russian (Soviet era) self propelled artillery vehicle in action.
The weapon is likely a 2S3 Akatsiya, which was introduced into Soviet military service in the early 1970's. The vehicle houses and operates a 152.4 mm howitzer and can store nearly 50 artillery rounds internally.
The crew usually consists of 4 to 6 troops. There is a driver, gunner, loader, and commander. In addition two ammunition bearers will stand behind the vehicle and feed rounds to the loader through an opening in the rear hatch.
In nominal conditions, the vehicle crew can fire a round approximately every 15 seconds, or about four artillery rounds per minute.
Although the artillery vehicle weapon system is considered to be outdated, we are seeing relics of war machinery being readily employed on many of the modern day battlefields, including Syria and Ukraine.