The 10 Best Boresighters

Owners of several rifles and handguns can skip adapters entirely with the Wheeler Professional. A magnet holds it to the end of the barrel, so one unit fits nearly any caliber with a steel muzzle, and Wheeler says each laser is hand-tuned. The body is machined aluminum wrapped in soft rubber, and Wheeler offers a limited lifetime warranty on it. The red dot fades outdoors past short range, and the green version costs a lot more.

One tool for most of a gun safe is the idea behind the Sightmark Triple Duty. A tapered spud slips into the muzzle and centers the laser across a wide range of rifle and handgun calibers. Twisting the cap switches it on, and Sightmark rates the dot at about two inches across at 100 yards. The tiny button cells drain fast, so carry spares, and a red dot is hard to spot in daylight at longer distances.

If you own a mix of rifles, pistols and shotguns, the CVLIFE 32-Adapter Kit packs a green laser and a full set of numbered adapters into one hard case. An extra sleeve steadies the laser in wide shotgun bores, and a push button turns it on and off, so the battery isn't wasted while you set up. Cheap adapters can sit slightly off center, so turn it in the bore and watch whether the dot wanders.

For little money, the StrongTools 7223 still covers a whole gun cabinet. A slim laser rod, a dozen color-coded adapters running from tiny rimfire bores up to shotguns, a spare battery and a small screwdriver all fit in a padded case. The rod touches the bore near both ends, which helps it sit straight. Buyers pick a red or green laser. It can't be used through a suppressor or muzzle device, and with fewer adapters some bores fit loosely.

Rimfire owners have fewer choices, and the Sightmark SM39021 answers them with a brass insert shaped like a .22 Long Rifle cartridge that drops into the chamber. Because the cartridge is so slim, the batteries ride in a small box on a thin wire, and a switch on that box turns the laser on and off. It suits one caliber only, and the box and cord are extra parts to manage while you work on the scope.

AR owners who want the simplest route can load the MidTen 223CAL-R3 into the chamber like a dummy round and close the action. It's machined brass, sized for .223 Remington and 5.56 chambers, and a spare set of button cells comes in the pack. There's no switch, so the laser stays lit from the moment the cap goes on until you pull the cells out. It fits one caliber only, and a loose chamber fit can nudge the dot.

Setting up a pistol red dot goes faster with the EZshoot 9MM-R2, a brass insert shaped like a pistol cartridge that sits in the chamber the way a round would. Screwing the rear cap down over the cells turns the laser on. It comes in a small tin with two spare sets of cells, each good for about an hour. It works in one caliber only, and the tin is easy to lose in a range bag.

Slug guns and turkey shotguns wearing a scope or red dot are what the Sightmark SM39007 is built for. It's a metal insert shaped like a shotgun shell that sits in a 12-gauge chamber, so nothing has to clamp onto the muzzle or the rib. A twist of the cap switches the laser on. It fits no other gauge, and its button cells run down in about an hour, so pack spares before a long session.

The CVLIFE U-CT-G brings the magnet-on-the-muzzle idea down to a budget price. A ring pattern on its magnet face helps you center it, nothing touches the rifling, and it charges from a USB cable instead of eating button cells. A full charge gives about an hour of laser time. It only grips steel barrels, and it hasn't been sold long enough to show how well it holds up over years of use.

Some shooters would rather not depend on batteries at all, and the Bushnell 743333 works by sight alone. An arbor slides into the muzzle, the viewer hangs in front of the scope, and you line the crosshair up with a printed grid inside it. Expanding rods fit most rifle and pistol calibers, and it packs into a fitted case. It's slower than a laser, and it shows alignment only through the scope, not on a target downrange.