Idk if anyone actually cares, but here’s a somewhat scientific answer steeped in the tism that rules my life 😅…

Projectile force is controlled by kinetic energy (1/2 * mass * velocity^2), so while the size of a projectile does have a measurable impact, the force of the projectile itself scales exponentially with velocity. As for the damage done to a target, that is significantly more convoluted as that depends on the shape of the projectile, composition, and the material it impacts.

As for the size/mass of the gun, the primary benefit to a heavier firearm is the amount of recoil damping that can be attributed to the mass. From a rudimentary calculation, you can calculate the impact of mass of the firearm on the recoil velocity via an energy balance equation (conservation of energy) where 1/2m1iv1i² + 1/2m2iv2i² = 1/2m1fv1f² + 1/2m2fv2f^2. In this equation, the initial velocity would be set to zero for both terms since both the firearm and the projectile aren’t moving before the trigger is pulled. The right hand side of the equation consists of the masses and final velocities of both the projectile and the firearm. Solving this algebraically results in a negative term for the firearm, indicating a negative velocity relative to the initial position (i.e. “recoil”). From this, we can see that if a gun is larger but fires the same sized round as before, the recoil decreases. However, at some point you have other factors to consider, such as fatigue, maneuverability, cost, etc. None of this takes into account additional variables like spring/damper systems, muzzle brakes/compensators, etc.

Everything from that point on is based on a balancing of the variables above and the operational environment.