n all its infinite wisdom, the U.S. Army determined after basic training at Ft. Polk, La., that I needed to be bussed to Ft. Leonard Wood, Mo. — a multi-use base about 50 miles from St. Louis — where I would receive advanced individual training (AIT) in my Army skill.

Combat engineer would be the MOS (military occupational specialty) I would be given upon completion.

If I hadn’t already signed up for officers candidate school, this meant I would have most likely ended up headed for Vietnam, where I would be assigned to a combat engineer battalion and put to work clearing fire bases, building airstrips, operating heavy equipment, assembling bridges and — most unpleasantly — clearing mine fields.

All of this holds a lot more fascination for me now than it did back then, but the Army hit a sweet spot when it gave me explosives training.

Ask me today how to assemble a Bailey Bridge, and I will remember pushing it across the frozen surface of a Missouri river. Ask me about clearing a minefield, and I will tell you the same thing I told the instructor trying to convince me it was perfectly sane to run your hand under an anti-tank or anti-personnel mine, find the detonator, flip it over, and disarm it.

“That’s what they make hand grenades for, Sergeant.”

But when they started teaching us how to blow things up — well, I just perked up and started paying attention. If you didn’t pay attention, you might blow yourself up.

But I was fascinated like a kid with firecrackers — really, really BIG firecrackers.

The Army used to hand out quarter-pound blocks of TNT, blasting caps and detonators like we really knew what we were doing — and they trained us well in their use — not that it has been of any subsequent use after the military.

It’s so hard to get blasting caps, after all.

But one of the real memories was the day we were taken to the range and shown how to build a “cratering charge.”

There might come a time in combat when you want to make a road inaccessible to enemy vehicles. Perhaps you want to make it impassable for that most powerful of battlefield weapons, the tank.

The instructors showed us a hole they had blown in the field that quite literally destroyed the dirt road. Probably 30 feet long, 12 feet deep, and 12 feet wide, this crater was created by burying three 55-gallon drums of diesel-soaked ammonium nitrate in the road.

That’s right. Fertilizer.

ANFO (ammonium nitrate/fuel oil) is a simple binary explosive that has been used in warfare and demolition since the 1950s. It is cheap and effective at moving dirt and rocks in mining operations all over the world.

ANFO is an extremely low-powered explosive — similar to black powder in the speed of the explosion. One way of rating explosives is by the speed the ignition travels from the point of ignition outward.

Thus ANFO, while it will move tons of dirt or rock, requires a LOT of material to have an effect. You don’t just carry 55-gallon drums of fertilizer around by hand, placing them like large firecrackers.

And, it is a binary explosive. Meaning two relatively safe materials must be mixed in a certain percentage for the combination to become explosive. 

In addition, ANFO requires a most serious detonation to make it work. The cratering charges in the Army were set off by single sticks of dynamite with blasting caps buried in each drum.

But good old American know-how and innovative marketing has found a way to make the stuff work in small quantities — and now there is a fun new target on the market that is legal, safe to use, makes a HUGE boom and is simple to concoct.

The most recognizable of several different offerings is called Tannerite.

And if you haven’t seen it work, go on the Internet and Google it. Or another, called ZomBoom.

Marketed as a binary exploding target, each package consist of a plastic canister of pure ammonium nitrate and a small packet of aluminum powder — a fine, gray powder that you dump into the canister and shake until the snow-white granules of AN are coated and gray-colored.

Instructions are quite specific here.

Place the canister on the ground, not near any materials that can be launched as shrapnel nor near any combustible materials.

Back off at least 100 yards, and shoot the canister with a centerfire rifle with a projectile velocity of at least 2,000 feet per second. Thus, rimfires, and pistol cartridges will not work as detonators — they do not have the shock power necessary to detonate this material.

Some Internet reports questioned the use of .22 centerfires, like .223. But we never had one fail — and the BOOM and dust cloud are most satisfying.

We placed one on the top of a fence post — in front of a safe backstop, of course — and it removed the top couple of inches of the post.

So what’s it good for? Not much of anything, really, except if you wanted to remove an aggravating stump in a field by placing a couple of canisters in it, and then executing a well-placed shot from a safe distance.

But then what’s a firecracker good for, other than a loud noise and quick flash?

This is not something you would use to build a bomb — how would you detonate it, for instance. And simple black powder is easier to use — and probably cheaper.

It’s simply something else to shoot at — the ultimate reactive target, so-to-speak. Boy, is it ever.

This target doesn’t ring like steel or fall down or swing or any of those other things we do to enervate the shooting experience. 

No, this one gives you a boom at both ends — and the noise and dust cloud are really impressive.

Best of all, it’s legal and fun, if something less than cheap.