OUTDOOR WRITERS tend to avoid the subject of gun safety because they think it is b-o-r-i-n-g. The fact is that it can be anything but. And therein lies a tale.

It happened one sweltering August day, more years ago than I'm willing to admit. I was just getting into the shooting game and Gus Petranek had agreed to teach me the rudiments of shotgunning. Gus was a good-natured old geezer -- in his late 60s, I guess -- and a longtime friend of the family. He once had worked as an electrician at the Brooklyn Navy Yard, and he also knew about things like ballistics, catching bluefish and fixing automatic transmissions. He was, in fact the kind of bargain-basement renaissance man one reads about but rarely encounters in real life.

In any event, Gus had a country place near Yaphank, Long Island, and it was in a nearby potato farm that I got the gun-safety lesson of a lifetime.

Gus and I had driven to the middle of the field in his decrepit '49 Chevy, and I helped him hump a box of clay pigeons out of the trunk and onto the dusty gray soil. We had a simple hand trap to throw the targets and I was hot to start shooting. But Gus wasn't in any hurry.

"Before we get started on these," Gus said, gesturing toward the clay pigeons, "I want to show you what can happen if you're careless."

He produced a brown paper bag, as if from nowhere, and removed a huge, softly ripe cantaloupe. This he propped into the chest-high crotch of a weed tree, a mimosa, I think.

Gus handed me a Remington shotgun shell of the old ribbed-paper variety. It was green and felt comfortably heavy on my palm, and vaguely illicit, like an oversized firecracker. The shell had a high brass base and was imprinted with the legend: Nitro Express 3 3/4 1 1/4 6. I hadn't the foggiest notion of what that meant but was duly impressed.

Gus dropped the shell into the right-hand chamber of his ancient Crescent sidehammer double, snapped the action shut and thumbed back the hammer. Clenching the stub of a White Owl panatela tightly between his yellowed teeth, he pointed the shotgun toward the cantaloupe -- which was about two feet away -- and let loose.

I really wasn't prepared for what happened. I guess I expected the fruit to break apart, with pieces of rind and seeds scattering about. But it wasn't like that at all. There was a great rumbling boom, like the muffled peal of distant thunder, and the melon simply ceased to exist. It had vaporized into a lingering sweet orange mist that hung heavily in the muggy air as it drifted toward the Atlantic Ocean. Left in its wake was a fragrant spatter of mush that dribbled slowly down the tree trunk. I touched the sticky melon gurry with my fingers and stood slack-jawed.

"Doesn't seem possible, does it?"

Gus's voice brought me out of my reverie.

"There's two basic things about shootin', son: Treat every gun like it was loaded and never point one at anything you don't want to shoot. You see what can happen. Keep them two things in mind and you won't go very far wrong."

We shot a few boxes of shells after that, and my shoulder ached for a week; the old sidehammer kicked like a lovesick jackass. I winged a clay pigeon or two, don't recall how many. But I've never forgotten the old man's words: "Keep them two things in mind and you won't go very far wrong."

A lot of water has gone over the dam since then. Gus went to his reward during the Johnson administration, and they tell me there's a shopping center where that potato field was; I never had the heart to go back and see for myself.

In the years since, I've done an awful lot of shooting, too. And I've seen people doing the dopiest things with firearms.

How about a hunter snatching a rifle by the business end and hauling it from the back seat of a car, the muzzle just inches from his chest? Or the one leaning on the muzzle in a duck blind, or forgetting where his companions are while swinging on a low-flying dove.

Another fun guy is the rapid-fire bozo who pivots from the firing line to clear a jam from his .45-caliber government model pistol. That sure gets those annoying spectators out of the way in short order!

Shooting and hunting are challenging and fun but unforgiving sports, with no room for daydreaming or carelessness.

I have it a little easier than most people, though, when it comes to handling firearms the right way. Whenever I find myself getting a bit lax, I take a refresher course by wandering back in my mind. It's all still there, clear as a bell -- a hot summer day, a dusty potato farm . . . and that incredible vanishing cantaloupe.