Troops said he would "pass" the test of using the machinery as they huddled with him under a camouflage net with drones flying overhead at Baker Barracks on Thorney Island.
The King was able to look through the aiming unit of the launcher, which when fired by an operator would take approximately four seconds to destroy an enemy target.
Lieutenant Colonel Maarten Magee said it was an "absolute privilege" to show Charles the kit, used to shoot down enemy threats such as drones and helicopters, and that the King got "a flavour of what we are facing".
He added the King was more interested in how the forces were dealing with modern threats, and he described the visit as a "once-in-a-lifetime experience for the regiment and the island to see him".
As Captain General of the Royal Regiment of Artillery, also known as the Gunners, Charles made his first visit to the 7th Air Defence Group Royal Artillery units at the military site on Thursday.
Charles spoke to military service personnel based in Saudi Arabia, Estonia, Cyprus and the Falklands via video link in the Junior Ranks' Restaurant, which he officially opened on Thursday, as their families watched.
The daughter of Sergeant Jack Harding based in the Falklands, Poppy, aged five, handed the King a letter after he spoke to the overseas soldiers.
Poppy's mother and Sergeant Harding's wife, Charley Harding, said presenting the letter was an incredible opportunity and the children would love a reply to add to their memory boxes.
"It's just nice that obviously with our husbands away and other family members, to have him come down and recognise that us as families do struggle as well, just show that extra support. I mean, it's great," Ms Harding said.
Meanwhile, Charles spoke to Jade McGowan, whose husband Andrew McGowan is currently based in Cyprus and does not have a date to come home yet.
The King asked about her nearly eight-month-old twins, Hamish and Brodie, and of her husband being away she said: "It's hard, we are doing what we can."
Speaking afterwards the 36-year-old said the King was "really friendly".
"It makes it a bit easier, doesn't, it to know that you're not alone and that don't feel that you are alone, because there is so much support," she said.
The Gunners were founded in 1716 and earned the Battle Honour Ubique meaning everywhere, as it is believed the regiment has served in every conflict the British Army has been involved with.
The King became the ceremonial head of the Royal Artillery on August 11 2023, in a role first taken by King George VI in 1947, followed by Queen Elizabeth II in 1952.
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