A Quick Guide to Shotgun Modification

Compared to a rifle barrel, with its lands and grooves, a shotgun barrel is simple: a smooth tube down which shot travels on its way (we hope) to a violent collision with a bird or a target.

Yet every year thousands of shooters pay good money to have a gunsmith tweak their barrels in search of denser patterns and lower recoil. Serious competitors don’t blink at spending lots of money to buy one more X on their scorecard, but is barrel work worth the cost for hunters and informal target shooters? Here’s the lowdown on the three most common barrel modifications.

FORCING CONES Look down the barrel of a shot-gun from the breech end. That ring you see in front of the chamber is the forcing cone, where the chamber tapers to bore diameter. Forcing cones are traditionally cut at an angle of 5 to 7 degrees, and as short as half an inch. Lengthening (from 2 to 6 inches) reduces the angle of the forcing cone to 1.5 degrees or less. The longer, gentler taper eases the transition of shot into the main bore, deforming fewer pellets and improving patterns. Many shooters feel noticeably lessened recoil after they have a gun’s forcing cones lengthened.

Approximate Cost: $75 per barrel.

The Verdict: It doesn’t cost too much, and it helps tame a hard-kicking gun.

BACKBORING Gunsmiths “backbore” shotgun barrels by enlarging the bore diameter with a reamer. Traditionally, 12-gauge bores measure .729 inch, give or take a ten-thousandth of an inch. Opening the bore to a larger diameter (usually around .740 inch) reduces friction as the shot charge travels down the barrel, increasing payload velocity, improving patterns and–in theory–reducing felt recoil. The gain in velocity is modest–about 20 to 40 fps. The reduction in recoil, to my shoulder, anyway, is unnoticeable in a hunting shotgun that may be fired no more than half a dozen times in a day.

However, backboring can turn a muzzle-heavy pig of a gun into a racehorse. I recently sent a 32-inch-barreled Miroku over/under to Briley (800-331-5718; www.briley.com) to have it done. After losing .010 inch of internal diameter, the barrels weigh 4 ounces less. I almost used to tip over when I mounted that gun, but now it’s lighter and quicker to the target.

Approximate Cost: $150 per barrel. You may also need new choke tubes to match the larger bore diameter.

The Verdict: No for recoil reduction. Yes to liven up a heavy barrel.

PORTING Porting, in which a series of holes are cut with an electrical discharge machine in the barrel near the muzzle, redirects expanding gases upward, suppressing muzzle lift. Larry Kelly of Mag-na-port International (586-469-6727; www.magnaport.com) invented porting in 1971, although the old Cutts Compensator offered similar benefits when it was introduced back in the ’30s.

I notice quite a difference in kick between ported and unported barrels, especially if I shoot more than a box of shells through the gun. If your gun is a cheek-biter, ports can ease your pain by redirecting recoil from your face to your shoulder, and the reduced muzzle lift means quicker follow-up shots.

Unfortunately, ports aren’t always suitable in the field. They make guns louder, and in duck blinds and goose pits a ported barrel can ring the ears of the person sitting next to you.

Approximate Cost: $80 for a single barrel; $120 for o/u’s.

The Verdict: Yes for target or dove guns. No for anything else.

Barrel work voids many factory warranties and is not for do-it-yourselfers unless you have digits to lose. Leave it to the pros–Briley, Mag-na-port, Seminole Gunworks (800-980-3344; www.seminolegun.com), Ballistic Specialties (800-276-2550; www.angleport.com)–to make your gun hit harder and shoot softer. It won’t cost you an arm and a leg, nor any of your fingers, either.