Like everything in life, GURPS has a spreadsheet for that: https://gamingballistic.com/2013/08/01/ballistics-spreadsheet-july-2013/
The most important elements are the velocity of the projectile, and it’s composition – in the case of a solid or jacketed projectile mass is the biggest factor, although hollow point projectiles will obviously do more damage through fragmentation – even with lower mass – assuming an unarmoured target
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