According to FractalSilence.com, a quarter of a kilo of C4 has a Blast Rating of 20 and a PEN of 6. Unlike grenades, the primary blast radius for C4 is only one meter (3.281 feet or 1.094 yards), and the secondary radius is only 2 meters (6.561 feet or 2.187 yards).
Each additional quarter kilo adds 5 to the Blast Rating, 1 to the PEN, increases the primary blast radius by a meter and the secondary by 2 meters.
Therefore a half kilo (1.1 lb) has a Blast Rating of 25, a PEN of 7 to a primary radius of 2 meters and a secondary radius of 4 meters and 10lbs (4.5 kg) has a Blast Rating of 105, a PEN of 23 to a primary radius of 18 meters (59.055 feet or 19.685 yards) and a secondary radius of 36 meters (118.11 feet or 39.370 yards).
“C-4”, or composition 4, is one variation of plastic explosive. The basic concept of plastic explosives, also called PBX (plastic bonded explosives), is to combine explosive chemicals with a plastic binder material. The binder has two significant jobs:
It coats the explosive material, so it is less sensitive to shock and heat. This makes it comparatively safe to handle the explosive.
It makes the explosive material highly malleable and you can mold it into different shapes to change the direction of the explosion.
The explosive material in “C-4” is cyclotrimethylene-trinitramine (C3H6N6O6), normally called RDX ("royal demolition explosive" or "research development explosive"). The additive substance is made up of polyisobutylene, the binder, and di(2-ethylhexyl) sebacate, the plasticizer (the element that makes the material malleable). It also has a small amount of motor oil and some 2, 3-dimethyl-2, 3-dinitrobutane (DMDNB), which works as a chemical marker for security forces.
Just recently, an improvised explosive device was detonated against the exterior wall of a building housing the Colorado Springs chapter of the NAACP, officials said. The explosion knocked items off the office walls but no one was injured. Read more at The Denver Post.