Of course you can wear a pair of safety glasses. Safety glasses are designed to protect our eyes when we are taking part in some dangerous activities. I think firing a handgun is a dangerous activity. I will never try that in my life. So I suggest you to wear a pair of safety glasses.
You may need to wear a pair of safety glasses. But I doubt that whether safety glasses can store prescription lenses or not. If the optician can give you a pair of prescription safety glasses, you don't need to wear your prescription glasses anymore. Or you can wear contacts and then put on a pair of safety glasses.
You can customize a pair of safety glasses that have prescriptions. But if you have high myopia, you can't customize the glasses. So I suggest you to consult in a nearby eyeglasses shops to see whether they can make that kind of safety glasses for you or not.