Once many years ago, without thinking I instinctively took apart a gun at a show I was very familiar with, all in just a few seconds, the owner almost had a heart attack.
Funny to me but, that guy was seriously upset!
I have never done it since without asking, and I always promise to return it to original.
I know several gun dealers who couldn't field strip a gun if their life depended on it. You can spot them pretty easily, the guns will have the signs of being wiped with oil but never disassembled.
Take pity on your dealer, be nice and most will let you take them apart if you show some competency
( Funny)
I will never forget the look on that guys face when he turned around and saw the gun in parts and me looking down the barrel with one eye!
Vern