I am interested in having some low profile snag free type novak night sites installed on my SA Mil Spec 1911. I understand that work to the slide is required. My question is, when I find a gunsmith to do the work, do I only leave him with the slide or do they require the entire handgun? My only experience to date is sending a complete firearm back to the manufacturer for work. Obviously I dont want to hand over my gun to a stranger, but I am sure I would get a receipt of some sort to prove the gun is not in my possession at that time.