They are Hogue rubber grips and I like them a lot. The factory grip had a thumbrest and that may be fine for shooting from a bench. But, in the field the thumbrest really got in the way for me. I have also replaced the worn grip screws since I took this picture with stainless hex heads.
Thanks for the info. I have a Mk III hunter, I didn't get the competition mainly cause the thumb rest wasn't for me. I do like the looks of the stock wood grips, but the Hogue ones look very comfortable.