I personally haven't, but my brother is training to be a officer and recounted this all to me when he was in Sandhurst, or Larkhill... (forget :P ).

He told me a few things about the experience, I'll roughly articulate what he said.

'Hey Qhost, so we got to witness a volley of artillery shells being fired. We stood in a field, and one of the officers used a laser-pointer (don't know the name) at the field next to us, and they sent the co-ordinates to the group of artillery 20 miles away. We waited for a moment and then suddenly we here a huge BOOM which was the guns firing, then moments later we here a WHEEEEEEEEEE as the shells fly through the air, and suddenly the field in-front of us just disintegrates as the shells hit.'

I then asked him about being next to one when it fires.

'Well, we have to wear 2 sets of ear-defenders because one just isn't enough, an internal and external one. What's incredible is when it fires you FEEL it. The recoil is so large and so fast that the gun displaces the air around it and you feel a rush as the air moves in to fill in the space.'

He also told me how the main cannon on a challenger 2 tank is so accurate that it can hit a target first time with something like 99.7% accuracy. He also said how only 3 challenger tanks have been destroyed; 2 of them by other challenger 2 tanks. When we invaded iraq / afghanistan (Not sure which one) - and we went up against their tank divisions, we didn't even bother with evasive manoeuvres because there cannons couldn't damage our tanks. We just drove at them firing.

Another interesting tibit from him: 'The UK has the ONLY anti-aircraft system that can pick up a US Stealth Bomber. Because the UK and USA often test out their weapon systems with each other, and the US flew over a stealth bomber just to see if anything can pick it up. And suddenly, one of our anti-air turrets activated and started to track this plane as it flew over our space. Bricks were shat'

He also talked about how awesome it was to control one of the turrets with an xbox controller. It must be unreal to move the control stick and have this HUGE multi-tonne weapon move smoothly with it.