Gunpowder's burning rate increases with pressure, so it will burst containers but just burns in the open. Ignition of the powder packed behind a bullet must generate enough pressure to force it from the muzzle at high speed, but not enough to rupture the gun barrel.
The gas constant occurs in the ideal gas law, as follows: where P is the absolute pressure (SI unit pascals), V is the volume of gas (SI unit cubic metres), n is the amount of gas (SI unit moles), m is the mass (SI unit kilograms) contained in V, and T is the thermodynamic temperature (SI unit kelvins).
Ideal Gas Definition. An ideal gas is a gas whose pressure P, volume V, and temperature T are related by the ideal gas law. PV = nRT, where n is the number of moles of the gas and R is the ideal gas constant. Ideal gases are defined as having molecules with negligible size with an average molar kinetic energy dependent only on temperature. At low temperature, most gases behave enough like ideal gases that the ideal gas law can be applied to them.