guns makes you invisible and doesnt deal damage?

So i am maing a first person shooter.(https://web.roblox.com/games/5097437953/VIP-AND-GEAR-World-at-War?refPageId=546f2ea6-964b-4dc2-955f-fc2d7722bdfb)

i have 2 issues with the guns. the first and biggest issue is that you go completely invisible on equipping it. the second issue is that it only deals damage on your screen. (for example on your screen you kill someone but on the other persons screen theyre still completetly fine) ive tried looking this up on the devforum but i couldnt find a fix that works.(i know that it has to do something with the local script or something) please help!