Folks, this is being over complicated. Though I must admit the suggestion on Page 4 to put powder under it to blow it out was not one of the solutions that crossed my mind....but I would be an interested observer.
IMO, you should be able to push the key/wedge out with firm finger pressure. Less than that it can fall out and be lost, more than that just tap it out with your ball starter, push with a patch knife, turn screw or eve a stick. If it is too short to push on, get a longer key/wedge.
If it is so tight you need to hammer it in and out, put a 10d finishing nail parallel to the jaws of your vise, put the key/wedge across the nail and give it a slight whack with a hammer to put a tiny bit of bend in it. Now place it back in the slot. If it is even harder to enter, turn it over so the bend is going the other way. Bend a little more or less if it is too tight or too loose. How do you tell if it is too loose? Well, that's when you have to order one or two replacement keys/wedges after each trip to the range. Once you get it right, it should last for 20-30 years or so. Mine have so far.