I do not teach fire arm use... fire arm use is not part of the Danzan Ryu system. Like others have mentioned, it would be better for people to go to a fully qualified fire arm instructor, for the type of shooting they want to do.
I do teach the gun disarms that are part of Danzan Ryu. (here I cheat, and start by teaching them how to unload and verify that a hand gun is unloaded.) But, I only teach this when the students get close to brown belt. During their white, blue, green belt... they learn all the techniques and movements that they will need for the disarms. (most of them are taught at white belt level) They just don't realize that yet which parts will also apply to a gun disarm. We can ramp up the intensity and speed of these techniques as well as working on maintaining control when uke doesn't comply. By the time we start talking about the disarm, they are fully capable of doing the techniques, at speed, with resistance and control. The only new element is the gun. Now they only need to work on the parts that are different... where is it pointed...
I actually disagree with many schools, who like to teach gun disarms on day one to new students or even to prospective students. I have seen this done quite a bit. I believe it is used as a marketing tool to "hook" the student by learning something "cool" right away. In my opinion, this sets up the student to fail, when their life is at stake... instead of taking the better option. (give them your wallet and run away) There is a big difference between practicing with toy guns, with the finger guard removed, on friends who want you to succeed ... and trying to take a real gun, from a real guy who does not want you to have it. My biggest fear is that a student will believe that they can do this, with a high probability of success, because it worked in class 7 out of 10 times against a water gun.
Many people don't realize that attempting a gun disarm is escalating the situation, not de-escalating. When the bad guy shows up with the gun, he has an expectation that you will comply. He has no reason to fear whether he goes home. As soon as you try for the gun, the bad guy is suddenly in a fight for his life. His fight or flight response may kick in... Where you could have tossed him the $40 in your wallet and run away... he now shoots you during the struggle or after the fact just because.
I just don't feel that marketing your school, by teaching a new person that you don't know, a cool thing, in a situation where he should mostly succeed... because you want him to sign up is the right thing to do... when that cool thing will get him killed. Before he learned that cool thing, he probably gives the money and runs... and survives. Teach them a kick or punch... have them break a board...