l have a real bad gag reflex... when they are putting on the braces, will it make me gag?

No. They do not go way back into your mouth.

When they take your molds (if you have not yet) you might have a bit of gag reflex, but it is not too bad. just make sure you breathe out of your nose

for the braces themselves, they do not go near the back of your throat so no worries there (:

just be sure to take some pain medicine afterward.

well the only thing l could see possibly making u gag would be this thing they put in ur mouth to keep it open to dry the glue from the brackets. the clear plastic thing makes ur lips come off of u teeth & u have this t-shape thing on ur tongue. it did not make me gag but it could be different for you. to me it stretched out my lips a little to where it felt a little bit odd..possibly a slight pain, but not too bad. also l have allergies so it made the back of my throat super dry because it is kind of hard to swallow. the hardest part with getting braces put on is the part l just explained. they do this after the put glue & brackets on each of ur teeth. after the glue is dry they will either send u home with spacers or (it varies depending on the way ur ortho wants to move ahead) they will go ahead & put ur wires in. putting ur wires in is not too painful, unless the wire sticks u in the cheek. its not as bad as it sounds. they clip it as fast as they can to the right length. after that u maybe get rubber bands that u will have to take in & out. these r a pain because they r hard for me at least to remember about putting them in. the most painful part is the day or two after they put new wires (tightening) on ur braces. ur teeth r moving so it is painful. it is hard to eat lots of food. just take a light pain pill like Tylenol & it will be a little better. good look. over all braces r not as bad as the seem. u get used to the feeling of metal in u mouth. oh btw, if a wire starts to irritate the inside of u mouth, just put a little wax on the spot. these r about all the little things l know. l hope this help!! good luck!!

It should not make you gag. Maybe when they have there fingers in your mouth if you are that bad it might a little bit. l have heard of a feel kids accidentally biting the dentists hand when they are putting them in from gagging.
On the other hand. When you have braces some people say it hurts some say it doesn't. It hurt me when l got my bands changed. l had to eat soft food for awhile. But it gets better!