Ok, here's the deal. If you haven't played Garry's Mod, some aspects may not make sense. Here is what was really going on:
1) The TV is a camera. I used it to get a good view without a HUD or anything during the explosion.
2) The blue beam gun is like the physics gun from HL2, only instead of attracting and throwing items, it has more control. You can rotate items and move them around. You can also control how far away from you they are. When the beam is active you have these controls. If you right click with the beam gun holding some object, it will freeze there until you release it by zapping it again and not freezing it or using the gravgun (normal HL2 version) to apply force to it.
3) The arrow gun is a generic model used for attaching special things in Garry's Mod. In this case, I was using it to attach...
4) Thrusters. They are represented by opened cans and turn white when in use. I applied eleven 30,000 pound thrusters to the top can. So, when I press a key bound to activate those thrusters on that channel (0), 330,000 pounds of force is applied to the end of the can, sending it down that entire distance faster than you can see. It happened between frames--within 33ms it went the entire distance.
So, when I release the barrel and activate the thrusters properly in the end, it goes down so fast that it causes the barrel to explode from the force, which ignited the other barrels, causing them to blow shrapnel all over the place. If those saw blade hadn't been on top, it would have all blown at the same time.