They label most parts for many items (non gun items as well) like that as to limit their liability. This way if you do it yourself and screw it up - they are "less liable" because they told you on the label to use a Pro. Personally I have a lot more faith in myself than just about any Gun Smith I know of. Many GS's are focused on "time is money" and they don't spend enough time on the fine details as far as I am concerned. Some are just butcher's! When I do my own work time is not a factor. If it takes me 5 times longer to do something I don't care as long as the final results are what I want. I will also redo something if I am not satisfied with what I have done. The words, "good enough" are just not in my vocabulary! While I may not be the most talented Gun Smith in the Country, none of them cares as much about my guns as I do!