Any other way to create bullets and or fix my issue?

I am creating an FPS game, and only one thing has been halting my progress. That one thing is raycasting. When ever I make a script that is supposed to shoot a ray from the barrel of the gun, towards the mouse, it always goes backwards. I've tried making the gun smaller, moving the barrel of the gun backwards, etc. I've even tried making a table of things the ray ignores, but that still didn't fix the problem. At this point, I am really frustrated as I can't get anything done for my game. Any help and or resources would be really appreciated. Thanks.