Winchester 12: Exploded View and Assembly

Winchester’s Model 12 slide-action shotgun has won the praise of hunters, competitors and soldiers alike during the 90 years and nearly 2 million pieces made since its 1912 introduction. Some of its fans have even gone so far as to agree with the company’s appellation of the gun as “the perfect repeater.”
  
The Model 12 was initially offered in 20 ga. only, which made it the first Winchester shotgun of that gauge and the first hammerless slide-action repeating shotgun to bear the Winchester logo. Two years after its introduction, it was available in both 12 ga. and 16 ga. The 12-ga. “trench” model with a 20-inch cylinder-bore barrel, perforated cooling sleeve and detachable knife bayonet was introduced in 1917. Without bayonet lug and cooling sleeve, it was listed in the Winchester catalog as the Model 12 Guard and Riot gun. A 28-ga. sporting version came on the market in 1934.
 
The gun’s basic mechanical layout—credited to design team chief Thomas Crossley Johnson in the company’s post-Browning partnership era—remained virtually unchanged throughout its life. It is of the old school, wherein the bolt locks up to a forged, machined, blued-steel receiver, and walnut serves for the buttstock and slide handle. Numerous machine operations, some complex in nature, were required to produce the receiver, and Winchester boasted that only the best steel alloys then available were used in the gun’s manufacture.
  
That quality at all costs approach eventually proved the Model 12’s downfall, however, as it collided with the reality of modern-day labor costs and manufacturing methods. Finally, in the late 1960s, the Model 12 was deemed too costly to keep in production. Attempts were later made to reduce its cost of manufacture, and limited sales of original-type guns were offered through the custom shop. By the early ’70s, though, the pump shotgun in general had lost much of its appeal, and the old warhorse was relegated to the heirloom and collectible sector of the market.

Nevertheless, the Model 12 remains beloved by tens of thousands of sportsmen who refuse to retire their “perfect repeaters” or think less of them.

Disassembly

After first ensuring that the gun is unloaded and the chamber is empty, place the receiver in a properly padded vise with the trigger guard upward to facilitate disassembly.

Remove the guard screw (46) and remove the complete guard assembly (45) from bottom of receiver (1). Note that the carrier assembly (60-65) may be removed from the guard by unscrewing the carrier pivot (64), which has a left-hand thread. Further disassembly of parts contained within the guard assembly should not be attempted, and replacement of parts 50 through 59 should be made only by a qualified gunsmith. Pull the cartridge cutoff (29) out of receiver. The breech bolt (31) may then be removed as follows: with the breech bolt unit in the full forward position, gently pry the ejector stud (30) from its seat in the inside of the receiver wall and slide the ejector to the rear and out from under the breech bolt and, then, out of the receiver.

Before attempting to remove the breech bolt, be sure the action slide is disengaged. Depress the rearmost arms of the breech bolt retaining lever (33) and slide the breech bolt almost all the way to its rearmost position. Then, lifting the breech bolt by its back end first, guide the left- and right-hand extractors (38, 41) up through the vertical slots on the inside of the gun’s receiver walls.

Although not normally necessary, the buttstock (47) may be removed by unscrewing the buttplate screws (49) and removing the buttplate (48), after which the buttstock bolt (4) can be unscrewed with a long, heavy screwdriver and the buttstock pulled away from the receiver.

To disassemble the breech bolt, remove the firing pin retractor screw (37) and lift the firing pin retractor (35) out of its seat. Pull the firing pin retractor spring (36) out of its hole. The left-hand extractor and spring (39) and breech bolt retaining lever are removed by drifting out their respective retaining pins (40 and 34). Remove the right-hand extractor by slipping the blade of a small screwdriver between the plunger (42) and the extractor and easing the extractor up out of its hole inside the breech bolt. Remove the spring (43) and plunger (42) toward the front. Reassembly is accomplished in reverse order.