Nebraska Dave News and Reviews

Hi, I'm making a Fallout pnp. Initially I was basing it off D&D 5e, but serious problems arose when it came to guns, I've found a very good system to tackle all kinds of guns but then another problems arose when calculating wheter or not an attack hits. If I want to make a system that resembles Fallout 1/2 for critical hits and body part targeting I need a d100, which directly clashes with D&D's d20 system, so I need to base it on something else, any suggestion that is not Dark Heresy?