I have two guns that I want to replace the stocks. 870 Express Mag, and a 770 in 300 win mag. I want to put a thumb hole stock on both. Is this something that I should be able to do by myself, or should I take it to a gunsmith? I feel like I am pretty handy, but I am not sure about it, if there will me many modifications needed. Do these typically just fit right up to the gun? A guy at Remington recommended Boyd's gunstocks. Does anyone have any experience with them? Thanks for any feedback.