Firing a gun against an immovable wall can theoretically increase the bullet's velocity due to the conservation of momentum, as the gun's recoil is effectively transferred to the wall. The speed of sound in the gun's materials and propellant gases plays a crucial role in determining how quickly the wall's effect can influence the bullet. If the gun is restrained, the bullet can receive more energy from the expanding gases, potentially doubling its velocity compared to a free-recoiling scenario. However, energy losses due to heat and shock waves must be considered, which complicates precise calculations. Ultimately, measuring bullet velocity under different grip strengths may provide a more straightforward assessment of these effects.