By Gen4, I can only assume that you mean Glock.
But, your post is far too vague for anyone to really make any sort of step towards posting an answer.
If you are talking about the Gen 4 Glock, then this is in the wrong forum.
"The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza
Baby Jesus cries when the fat redneck doesn't have military-grade firepower.