The phrases "gun smithing" and "shotguns" may not immediately associate themselves in your mind. You may be more likely to take your 1911 pistol or rifle in for some custom work. Yet several specialists have carved out a niche delivering scatterguns that deliver higher performance.

The pump guns arrive with precision-machined barrels that deliver tight shot patterns and allow officers to respond to threats from further distances and in various scenarios.

Mike Shain of AIMPRO Tactical, who has taught numerous firearms classes to officers, is clearly not in the "point and shoot" camp. A Mossberg 590A1 becomes a precision weapon, after one of his action jobs.

He focuses much of his attention on slickening up the gun's magazine tube.

"If you can't get a round into the gun, you're out of business," Shain says. "That magazine tube is a critical part of the system. We want it to be slicker than snot."

Shain uses a series of proprietary tools and abrasives to deburr all metal-on-metal parts and uses heat-applied metal conditioner and dry lubricant on parts.

A process known as Magnaporting improves accuracy. Elliptical-pattern holes are cut in the top of the barrel. The holes, which are angled backwards, function like metering ports and force the barrel forward and down. This helps reduce felt recoil and reduces muzzle jump, which is caused by the force of recoil itself and gas pushing back toward the receiver.

The work allows officers to engage their targets from 20-30 yards, which is ideal for responding to a local "stop and rob" convenience store incident. Depending on the barrel, officers can typically achieve a 4-inch shot pattern at 50 yards out using regular police buckshot.

Along with AIMPRO, Vang Comp and Wilson Combat are two others that offer shotgun modifications.

Hans Vang Comp's shop takes a different approach to modification. He overbores the barrel, essentially taking a 12-guage barrel and turning it into a 10 gauge. He creates a choke inside the barrel of the gun to improve performance of buckshot. Van Comp also lengthens the forcing cone, a funnel-shaped transition area between the chamber and barrel. This softens felt recoil.

An array of buttstocks, slings, rails, muzzle breaks and other accessories can also be added to transform an "out of the box" gun.

View our photo gallery of custom AIMPRO Mossbergs and "Arsenal" firearms reviews of a Vang Comp Remington and Wilson Tactical TR-870 .