They slowly shrink back from him as he berates them for untidiness, bad posture and even for smiling.
But this drill sergeant has a twinkle in his eye - because the young men are not new army recruits, but people who have signed up to a day of military gaming simulation.
They will spend the day playing their favourite computer battlefield games - for real.
Once the sergeant has given them a shake-down, the men are given their camouflage clothing and a mission objective before they are shown how to use their infra-red weapons.
They are then split into teams and led off into a wood to start gaming.
Smoke bombs begin to flare and the woods turn an eerie green as coloured fog rises from the ground.
The players dart excitedly in between the houses of an inflatable "village", dodging enemy fire in an attempt to capture a jerrycan from the opposing team.
Both men served with the Royal Engineers for 24 years, and carried out tours in Iraq, Afghanistan, Bosnia and Oman.
They have used their military experience to offer gamers a taste of what it is like to be in the army.
"Our unique selling point is the realism, so all of the kit they wear is pretty much the same as armies around the world wear," says Mr Belcher.
"But it's the guns they are using that really bring the game-play to life."
So far, things have gone well, so Mr Belcher and Mr Skelton are confident about the concept of their business.
But now that it is up and running, they realise that it is still a challenge to keep it ticking over.
"We are not taught how to run a business or market ourselves in the army," says Mr Belcher.
Dealing with the bureaucracy of tax or national insurance has been tricky, so - like many people who are setting up their own companies - they have had their "fair share of sleepless nights", he says.
Mr Belcher and Mr Skelton are just two of the more than 19,000 people who left the armed forces last year.
The Ministry of Defence predicts that some 96% of them will find a new job within six months, in spite of the current unemployment rate of more than 8% in the UK.
But it can be very difficult for service personnel to make the transition back to civilian life.
"Many ex-servicemen can feel a huge sense of loss when they leave the military," says psychotherapist Maggie Heap.
"They miss the camaraderie and they miss the bonds they formed on the front line - it's something you can't really replicate in the corporate world."
Many ex-personnel find it hard to adjust to the back-biting found in many big companies because they are so used to supporting each other and working as members of teams, she says.
This helps explain why so many of them are keen to set up their own companies when they leave the forces - even though in reality many of the skills they learn in the military, such as organisation and the ability to keep calm under pressure, can be easily transferred to their new jobs, she says.
Be the boss
When it comes to starting up businesses, former military people face the same problem as everyone else, namely that the banks are often reluctant to lend money.
With this in mind, The Royal British Legion, the charity for former soldiers, has set up a special fund called "Be the Boss".
Funded by a Treasury grant from the UK Department of Business, Innovation and Skills, the scheme is available to anyone who has served at least one week in the forces.
The scheme also offers training and mentoring support to UK Services leavers on how to run a successful small business.
The fund has been running for nearly 18 months and has proved incredibly popular.
"We had 1,000 people apply in the first year - and now we have 2,000," says Shegufta Rahman who leads the project.
Ms Rahman says the number has risen for a number of reasons:
"We have a lot of people coming to us because they can't find jobs," she says, "or they've lost their jobs and they want more control over their life and their livelihoods."
One of those who has benefited from the Legion's scheme is Barry O'Connor. He joined the Royal Marines in 1999 aged 19 and later became one of their personal training instructors.
"I don't want to sound soft, but I'd met a nice girl and I wanted to stay in the UK to be with her," he says.
The banks were reluctant to lend him money, however, so he applied to the scheme.
"It looked like very hard work," he says. "You're not guaranteed any money and you have to go through a pretty rigorous process to get the funding."
But, he says, the mentoring that the British Legion offers him is "invaluable".
"They constantly ring me up and bug me about things - and I can ask them for help. We're a pretty arrogant lot," he says with a chuckle, "so we need that business advice and we need someone to turn to."
Like many other former military personnel, Mr O'Connor wanted to set up his own business rather than work for someone else.
"I'd sweated blood, quite literally, to become a PTI," he says, using military jargon for his former job as a personal training instructor.
"And I didn't want to work for someone who hadn't done the hard work I have - or experienced what I've experienced."
"Civvy street is totally different from the military," he says.
"Things don't get done as quickly. If someone says they'll get something done in a week - take that to mean two weeks."
But he also says they can take the skills they learnt in the military and apply it to their new lives.
"It's not that different from Afghanistan. You want to go from A to attack B and you get ambushed en-route. It's the same in business," he says, before adding, almost as an after-thought, "but without the bullets."