It is legal for deer and depending on how far you want to shoot, it should be a great choice. I have a 18" Grendel, but I haven't killed a hog or deer with it. I use a 6.8SPC and it does the job every time. The two calibers are very similar.
A 12" can certainly do the job. A buddy of mine hunts with a 12.5" that he built. He target shoots with it at 300 yards and shoots deer and hogs out to 150, IIRC. He has shot pigs at 100 yards at my place.