A few months ago, while strolling the exhibition hall at a hunters' convention with my friend McNally, a case on a gun dealer's table caught my eye. Any gun case is likely to pique my curiosity, but this was an oak and leather trunk showing the patina of many years, and confronted with one of those, I become much like the fabled gentleman of over-amorous inclinations of whom it's said that he would make advances to a birdcage if he thought there was a canary inside.

There was a canary in this one, a little bedraggled, but still a canary--a trim little 20-gauge with the name of a very famous gunmaker on the locks and an extremely prestigious London address on the rib. I asked the proprietor if I could take it out and, with his assent, looked it over for a few minutes, put it back, thanked him, and wandered on.

"I wish I had a notebook," McNally said.

"Why?"

"So I could write down all the things you did with that gun. Is it worth the price he's asking?"

"Nope. The rib's about to come loose, the action's off the face, and the stock-head may be split."

"Repairable?"

"Sure. Two or three grand should put it right as rain."

"That's what I mean," McNally said. "I could look at it for a week and not see anything wrong. You oughtta write something about how to spot problems in older guns, how to tell the difference between the jewels and the junk."

I'll leave it to you to decide whether I oughtta, but McNally was right on one count, at least: In the gun world, there's no jewel like an old one. Older guns touch me in ways that new ones usually don't. Like some women, they're all the lovelier for showing a bit of mileage, for looking as if they've been somewhere and done something, and gained some character because of it. There's no beauty quite like beauty shaped by time.

Unfortunately, time and use can exact a toll, and the effects aren't always readily apparent. (I'm talking only about guns here, and from here on. The mature-woman simile is apt to get me into trouble if I take it any further.) Some things are best evaluated by a good gunsmith, but that's the second step. The first is to decide whether the gun in question is worth a professional vetting or whether it's best left to become someone else's problem.

Among the proverbial lock, stock, and barrel, pay close attention to the barrels. They're apt to be the most expensive part to repair, certainly to replace. Deep dents and fat bulges are easy to see; small ones aren't, necessarily, but they show up better if you point the barrels toward a source of light, so their surface picks up reflection, and peer along their length as you rotate them. If you can get the straight-edged shadow line of a door- or window-frame reflected down their length as well, so much the better for seeing any waves, ripples, gentle bulges, or other such irregularities. Hold them at arm's length and sight down the rib to see if it's dented or crooked. If it shows jogs or bends, there's a good chance it has come loose and been resoldered at some time; putting one back on and getting it straight is a tricky job. And if the rib has been reset, the barrels will have been re-blued or re-blacked.

If the ribs don't show any evidence of having been reset, ringing the barrels will tell you if they might soon need to be. Hang the barrels on your finger by the lump, and strike them with a backhand flip of your fingernails. They should ring with a clear, sweet, bell-like tone. If they don't, if they sound dull and clunky, the solder holding the ribs on is beginning to crystallize, and something is likely to come loose in the near future. (On the other hand, you can make the best set of barrels in Creation sound like real dogs if you hold them by the extractors when you ring them. It's an old gyp-trader's trick to knock down the buying price. I mention this not to suggest that you do it, but rather so you won't have it done to you sometime.)

It's not always easy to tell if a set of barrels have been shortened. American barrels should measure precisely to the inch, not in fractions; those on European guns might not, because Europe operates on the metric system. The muzzles should be perfectly square in relation to the centerline of the rib, and they ought to be very close together, even touching--although the muzzles of ultralight small-bores might not.

Shortening barrels isn't always the kiss of death for the way a gun performs. Sometimes, all it does is eliminate the choke. But shortening also can change one barrel's point of impact. Shooting at a patterning plate is the only way to find out if that's happened.

English game guns have always been bored with 2 1/2-inch chambers, and so were a lot of older European guns. The Continental pieces typically are marked with chamber length in millimeters--65 for 2 1/2 inches, 70 for 2 3/4 inches. Some English guns have chamber-length stamps, but most don't. They are, however, marked to indicate the shot charge appropriate to their level of proof, so a stamp of "1 1/8" on the barrel flats means 2 1/2-inch chambers, and "1 1/4" means 2 3/4-inch.

The buyer's caveat here is that the stamps show how a gun was originally chambered, not necessarily how it's chambered now. A lot of them have been rebored to 2 3/4 inches, but unless the work was done in England, the gun won't be restamped nor, more important, will it have been reproofed. The problem is that removing steel from British barrels--through lengthening chambers, refinishing, removing pits, or whatever--can affect their integrity. It's wise to have a gunsmith measure the barrel walls of any older English gun you're thinking of buying, even one that appears pristine, and it's a necessity for a game gun that's been rechambered. Otherwise, you're taking a chance on buying an expensive pig in a poke.

If you find dents in the sides of the barrel lump up near the hinge-hook, someone probably has tried to tighten the action with a hammer and punch, a shade-tree approach that mercifully isn't as common as it used to be. Pass on any gun that shows such evidence.

In a break-action gun, the hinge is subject to wear, and no gun, no matter how meticulously built, is immune. Slamming the action closed, which all too many shooters do, only accelerates the problem and puts unnecessary stress on the fastening system besides. Wear in the joint ultimately affects the relationship between the barrels and the breech face; when gaps begin to show, which you can see by holding the gun up to the light, it is said to be "off-face." It may be off a little or a lot. A badly worn joint is easy to spot; the barrels will rattle around when the action is open, and oftentimes you can feel some play even when it's closed.

To detect lesser degrees of wear, take the fore-end off, hold the gun by the barrels, and thump the buttstock with the heel of your hand--on the sides, on top, all around. The more vibration you feel, the looser the joint. This test doesn't work very well if the gun is a self-opener (which includes all Purdeys) because the opening-assist springs keep the barrels tight against the frame even when the fore-end is off. For these, you need to hold the top lever all the way open, let the barrels tip just slightly, and flex them; you'll be able to feel any slack.

What to do about a gun with a worn hinge depends on how worn it is, what its condition is otherwise, how badly you want it, and how good a bargain it is. A gun that's slightly off-face will stand good service for a long time to come, and don't dismiss it out of hand even if it's badly off, because any gun can be rejointed.

Inspecting lockwork and ejectors and such is a gunsmith's job, but a close look at the exterior will tell you how suspicious of internal problems you should be. Buggered-up screw slots are classic symptoms. They mean that some ham-fisted clod has been at work, and if he can't take out a screw and put it back without chewing it up, then anything he might have done inside probably wasn't done any better. Don't be surprised at what you find; one gunsmith recently told me of finding a lock that had been "repaired" with a safety pin.

Naturally you'll want to check out the functioning of any gun you're seriously considering, and you can get a good idea of what shape the locks and ejectors are in just by testing them with snap caps. You can check the sears by pulling the triggers with the safety on, then clicking it off without touching the triggers. If one lock or the other trips, you're probably dealing with a bad sear.

Try the ejectors one at a time and then together. Both should trip at the same time, just a fraction after the locks cock (you can hear the locks if you listen closely) and should toss the snap caps about the same distance. If one requires a hard jerk on the barrels, it's going to need some attention.

Wood being both more mutable and less durable than steel, stocks are heir to all kinds of ills--shrinking, swelling, splits, chips, rot from years of soaking with petroleum-based oil, you name it. I've never seen a gunstock infested with termites, but it wouldn't surprise me. Look for cracks behind the tangs, behind the plates if it's a sidelock, and in the wrist.

As with loose action joints, stocks offer a lot of options, and the same considerations apply. Many (probably most) problems can be remedied--including, if the stockmaker is really good, some that appear a total loss. Matters of fit usually can be accommodated by bending, lengthening, or shortening. And any gun can of course be restocked.

The little 20-bore that set McNally off on all this showed some of these problems. The barrels didn't ring well; it was just enough off-face that I'd be thinking about a re-joint job if the gun were mine; and there were hairline cracks behind the top tang and the right-hand lockplate. One crack is one crack; two visible cracks in that part of the stock may in fact be one big one.

This isn't to say that is was a gun to avoid. On the contrary, it would have been a good buy if the price were low enough to accommodate some repairs and still leave you with something reasonably worth what you had in it. And when you're buying an older gun to shoot, that really is the bottom line.

I told McNally all this, or most of it, while we browsed around the exhibition hall, and as we neared the last aisle, he said, "This is definitely something you oughtta write. Let's go find some place to sit down and you can tell me more, and we can have a couple of beers."

One thing about McNally--he's full of good ideas.