When i first made a char I had all kinds of troubles. I didn't use a shock mod or any other ele mod on a wep thus i used alot of ammo and i constantly died. I added points to skills I'm use to in fallout unsure of where to add points. I searched youtube till i found a video build called Time Sniper and now i love the game! One hit killing just about everything and if i don't i tinker up my wep till I do. Only problerm I'm having now is it won't let me add the silencer muzzle on my plasma rifle. It will let me install a zap mod but if i do will it replace the plasma mod and make it electric or will it do plasma+ shock? I'm waiting to find a corrosive mod.

You can only have one mod per slot, so you can't use multiple muzzle mods. If it didn't you could just slot every kind of elemental damage onto your weapon and it would render one of the science weapons basically not unique. 

why won't it let me install the silencer muzzle mod? It should replace another mod i have on the plasma rifle won't it? even when i didn't have any mods it still wouldn't let me install it....do i need to raise science skill to install it?