The only thing Ive noticed on Mule Deer is the 22s will blow up on the shoulder or knuckle of the shoulder and you have a hell of a tracking job on your hands and hopefully a good dog....Ive seen it more than a few times so use care to shoot behind the shoulder..I suspect a Barnes X type bullet would bust the shoulder bone..

Ive notice my 6x45 will bust the shoulder and kill the animal with a heavier bullet like the GS Customs or old Barnes 75 gr bullet will do it every time.....But its the equivalent of a factory .243 for all practical purposes.

I suppose the secret is bullet placement and bullet selection. I prefer the 6x45 over the .223 mostly because Ive spent a bundle on building the 6x45