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 Law Introduction: Discusses the ideal gas law PV = nRT, and how you use the different values for R: 0.0821, 8.31, and 62.4. Ideal Gas Law Equation The Ideal Gas Equation is given by: