This gun is produced for Smith & Wesson by Howa Machinery, Ltd., Nagoya, Japan. It was developed by Howa and has some minor modifications made by Smith & Wesson engineers.
As usual with gas-operated shotguns, the gas mechanism of the Model 1000 is in the front of the magazine tube, which is concealed by the fore-end. The barrel is fixed during firing, but can be removed easily without use of tools by following the well-written instructions furnished with the gun. This facilitates cleaning and permits changing of barrels. Spare interchangeable barrels with various lengths and chokes are available at extra cost.
Operation is by means of a short-stroke, floating hollow piston designed to give a prolonged push instead of a hammer-like blow. (For detailed explanation of this system, see Question and Answer “M14 Gas Cylinder,” The American Rifleman, Feb., 1963, page 64.)
Powder gas enters the hollow piston through a piston hole aligned with two ports in the barrel, and fills the space within the piston and cylinder. Initial movement of the piston takes the piston hole out of alignment with the gas ports and prevents further entry of gas. The trapped gas expands and drives the piston, piston connector ring, action bar assembly, and breechbolt base rearward. After these parts are driven back approximately 3/8”, the breechbolt base cams the locking block in the breechbolt downward out of engagement with the barrel extension. This gives time for the pressure in the barrel to drop before unlocking occurs.
When the piston hole aligns with the gas-escape slot in the cylinder, gas used to operate the mechanism is exhausted upward through two slots in the top of the fore-end. The piston and connector ring are stopped after 1-3/16” travel, but the action bar assembly and unlocked breechbolt continue to the rear until the fired shell is extracted and ejected. The rearward moving breechbolt cocks the hammer and compresses the action spring in the Buttstock. As the breechbolt is driven forward, it chambers a loaded shell.
A highly-desirable feature of the Model 1000 is its pressure-compensator valve assembly designed to stabilize variations in gas port pressures and thereby adapt the gun to a wide range of loads. Located in the front end of the gas cylinder, this valve assembly has a tough, springy plastic piece between two cylindrical metal parts. Gas pressure causes the plastic piece to be compressed according to the amount of pressure exerted, and thus varies the amount of space for gas expansion.
As with most semi-automatic shotguns, shells are loaded into the magazine through a port in the receiver bottom. A magazine capacity pin extending laterally through the magazine tube reduces total capacity of the gun to three shots as required by Federal Migratory Bird Regulations. Removing this pin increases the magazine capacity to three shells or total capacity of the gun to four. The gas system at the front of the magazine limits its capacity to three rounds although the total length of the tube and fore-end are quite long.
The crossbolt safety in the rear of the trigger guard has a red band that is exposed when the safety is disengaged. It can easily be reversed for left-handed use by following instructions provided with the gun.
A ventilated barrel rib fitted with front and mid-rib metal beads is a standard feature of the Model 1000. The rib is 5/16” wide and is finely checkered to reduce glare. The receiver top in line with the rib is finely grooved.