16ga.com ~ View topic

That is a good question and a good beginning. There are a couple of things to look for that anyone can see if the bore is clean. Thats where you start. Clean the bore if it is not. You need good reflective surfaces to examine the bores properly.

In a well rounded, perfectly straight bore, the chamber, the bore line and the muzzle will all line up perfectly like the concentric rings of a target. You might also see a series of reflected rings. Just steady the barrel on a supportive surface and carefully line them all up against a uniformly plain white or light colored background with even lighting. The background is absolutely essential to the examination. So find a good one. Don't settle for less either or you might misjudge the gun due to background introduced reflections that conflict with the visual process.

Most mass production barrels will have a very minor bit of run out in the bore. That is okay if the runout is exactly that, very minor. If you see a noticable curve, the barrel is NG. also, look at how round the rings are. If the bore is noticably ovated, pass on it. The straighter the bore, and the rounder, the better.

For single barreled guns with a rib, the rib and the bore should point to exactly the same spot at about 20 yards or more. The rib should be squarely on top of the barrel running straight down the center. If it is noticably off line, pass on the barrel. It will never line up well enough to point the bore accurately. Its the same with the bead on a plain barreled gun. However, beads can be fixed if they are not way off. Ribs can't easily or cheaply.

With doubles of either type, O/U or SxS, the two bores should be matched for runout and muzzle alignment. If both bores have a bit of runout, that runout should be oriented to match. In an O/U. look to see if the runout is oriented vertically and if an SxS, horizontally.

In an O/U, a very, very, minor bit of runout to the left or the right is probably ok if both bores are oriented to match. These pairs usually will have the rib tweaked to compensate. So look to see if the rib points the muzzles where they should be. Put the rib on a distant object and sight though each bore independently. If they both cover the same object as the rib, then the barrel set has a good chance of hitting there.

With an SXS, the rib must be oriented dead between the barrels. So compensating the rib does not work as well here. Make sure the rib and both barrels cover the same point though just like the O/U set.

Be aware that an O/U barrel set is compensated when it is built so the bottom bore points very slightly above the the top bore. About an 1/8th diameter or a tad less is about right depending on the design and the gauge. Look for this and don't mistake this slight bit of upward compensation as a mistake. It must be there for both barrels to hit to the same point at 40 yards. Its the same for an SXS only its done horizontally. Both bores will appear a tad inwardly cross-eyed. They should.

However, If you notice that one bore points or curves left and up and the other points right and down or some other cockeyed way, these barrels will never shoot together and will also be miserable to line up with the rib. Chances are the stock won't be able to be adjusted enough to compensate for a proper POI. It might be possible to correct one of the barrels of the badly oriented pair to shoot where you are looking but not both.

When learning this skill as with all others, take your time. Look at a lot of barrel bores. It takes a bit of practice and experience to easily see the flaws but time and practice will teach you.

However, once you learn to properly see these flaws, pass on the gun that has them. Don't risk it even if the price is very reasonable. That is probably why the gun is discounted as much as it is all other things being equal. This advice also applies to the used gun market--especially the used gun market. Fixing misregulated or out of round barrels is possible, but usually very expensive. There are no guarantees on after market work either. also, once monkeyed with, the warrenty is null and void. As often as not, with bargain doubles, if you get a bad one, little will be done to correct it in a reasonable amount of time if ever--especially in an already stressed market. So if you buy it, you own it unless you can palm it off on the next guy--which happens all too frequently.

Finally, always confirm that your barrels shoot together and reasonably close to where you are looking when the gun is properly mounted. A correct POI is the single most important thing about any shotgun. You can't hit what your gun won't cover. Any pair of barrels that puts both patterns within 2 inchs of each other or better center to center at 30 yard and reasonably close to what you are pointing at will do the job. Any more spread than this between where the barrels hit, or a gun that shoots much more than a foot off of what you are looking at does not suit you. It is unlikely it can be corrected to do so either. Pass on it and keep looking. 16GG.

PS: This advise about barrel orientation applies mainly to modern, mass produced doubles. Modern paired barrels are normally hammer forged, stress releaved, then straightened again if needed. The muzzles are then bored and threaded for the tubes. The bores and chokes should be dead on and fairly straight before they are brazed together. They are then placed in a jig that holds them together exactly as they will come off fully assembled with side and top ribs etc. They are or should be lazer collimnated to confirm they will shoot close together within spec. However, how well all of this is done depends on the skill of the work force and how much time and trouble they can take to do it right. When the process is speeded up or streamlined for expediency, the product usually suffers. In times of haste due to stressed capacity and a stressed work force, quality control is usually the first victim sacrificed.

Most of the better older doubles made prior to WWI and many made prior to WWII had the barrels oriented and regulated for POI by wedging them in the middle, shooting them in, rewedging them until correct, then soldering them together. The cheaper, mass produced guns of this era were visually oriented and jigged like today prior to soldering but the better ones also had the chokes reamed to compensate and correct the poi so both barrels shot close. That is why you often see a wider variation of the choke points stamped on the barrels. The old timers knew that POI is more important than pattern precentage. Plus it was more common to have another set of barrels with different chokes fitted.

Sometimes its hard to visually verify a vintage gun. As with any double, verify what the eye tells you by shooting them for POI. Sometimes, its the only way to tell with these older guns. Unless they've been monkeyed with, most of the better one will shoot very closely together.