These do exactle what they are supposed to do keeping sand, dirt and small debris out of the barrel. Yes you can shoot thru them, but be sure you have a few extras to replace the one you just shot through. 

The tan and black colors are the better choice. Red creates the false impression that the gun is a toy. This could, to the unknowing person or young person, who has been spoon fed that toy guns have red barrel tips, that a real weapon is just a toy and they kill someone playing with it as if it were a toy.