Most of those skins firing animation made the it seem like the player holding the gun out from his body. The recoil looked ridiculous, especially for the ump. With a gun flying around like that, it makes me wonder if the person who skinned the gun even thought about the gun having a stock.
If you're looking for realistic/cool looking guns, you have to do it one by one unfortunately. I've found that its easier to look for a skin for a certain gun than get a whole pack, just to use one particular skin in the end.