(Do handguns come out in every conflict? No. But if you look at what crops up again and again, pistols are in the top three along with hand-to-hand and improvised weapons.)
Effectively, shooting's as essential a skill to an actor today as skill with a rapier was to Shakespeare. We're in the middle of a more or less equivalent era.
And now there's some wondering how I got to that conclusion. Let me elucidate.
Shakespeare lived during the rise of the rapier, a weapon that's lousy on a battlefield but proved handy for civilian use. The design also made it easy to customize for those who liked to flaunt their wealth and style. And while any gentleman could (and many did) take the time to use it, there were a number of (usually younger and hot-tempered) men who practiced as often as their lifestyles would let them.
At the same time, a number of masters popped up, establishing schools and writing manuals. Agrippa and Morozzo already had manuals published by the start of Shakespeare's career. George Silver, Fabris, Di Grassi, and Capo Ferro were all published by the time Shakespeare had penned his last play.
What this meant was that every year, more and more members of Shakespeare's audience were educated about rapier combat: how it worked, what was possible, what was likely, and what was preposterous. He and his actors needed to know their stuff or pay for it at the box office (or in flying tomatoes).
Fast forward to today, where the handgun (a weapon of extremely limited use on the battlefield) is being owned and carried by more average Americans every day, in a trend that's been lasting 30 years or more. In 1986, 16 states banned ordinary citizens from carrying concealed weapons. By the turn of the millennium there were only seven. The last holdouts (Illinois and D.C.) had their laws struck down by Supreme court decisions in 2013. Today there's an estimated 12 million concealed license holders all across the country.
An entire cottage industry follows the customization and decoration of these weapons, from the commercial to the gaudy to the beautiful.
And since the 1960's the practice of handgunnery has evolved from a training system for police officers into a martial art. Masters like the late Jeff Cooper, Mossad Ayoob, and Don Mann are writing books and teaching classes across the country. Different schools of thought and techniques are cropping up all the time. My own gun classes for actors evolve about every six months nowadays.
In other words, safety and aesthetics aside, it's getting harder and harder for an audience to suspend disbelief in an untrained gun-toting actor. So if you're going to tread the boards, you might want to get in some range time too.