Читать книгу The Gun Digest Book of Firearms Assembly/Disassembly Part V - Shotguns - J B Wood - Страница 13

Browning B-2000

Data:	Browning B-2000
Origin:	Belgium
Manufacturer:	Fabrique Nationale, Herstal, for Browning, Morgan, Utah
Gauges:	12 and 20
Magazine capacity:	4 rounds
Overall length:	46 inches(with 26-inch barrel)
Barrel length:	26 to 30 inches
Weight:	7 1/2 pounds

Introduced in 1975, this sleek autoloader was Browning's first entry in the field of gas-operated shotguns. While all guns of this type have operating systems that are somewhat similar, the B-2000 gas mechanism has some different features, including a valve that regulates the ported gas, allowing the use of a wide range of loads. For those who are accustomed to the large and simple parts of the venerable Auto-5, the takedown may have some surprises. There is an inter-dependence of small parts, and the amateur should proceed with caution.

Disassembly:

1. Pull back the operating handle to lock the bolt in the open position, and set the safety in the on-safe position. Unscrew the magazine end cap, and remove it. Take off the barrel and forend toward the front, and remove the forend from the barrel toward the rear.

2. Restrain the gas piston at the front of the magazine tube, and push out the gas piston bar toward either side. Caution: The piston is under spring pressure, so control it and ease it out.

3. Slowly release the spring tension, and remove the gas piston assembly and its spring toward the front.

4. Remove the gas cylinder plug from the front shaft of the gas piston valve.

6. Remove the gas pislon valve toward the rear..

7. Restrain the bolt, operate the carrier latch, and ease the bolt forward to the closed position. With a non-marring tool, push out the trigger group retaining cross pin toward either side.

8. Move the bolt about 1-1/2 inches toward the rear, depress the carrier latch, and move the guard unit a short distance toward the front. Tip the front of the trigger group slightly downward, ease the bolt back forward, and remove the trigger group from the bottom of the receiver.

9. Restrain the carrier, and push out the carrier pivot pin.

10. Remove the carrier upward. Note that the carrier dog and its plunger and spring are retained on the rear arm of the carrier by a cross pin that is heavily riveted in place, and removal is not advisable unless necessary for repair.

11. Remove the carrier spring from its recess on the right side of the trigger group.

12. Move the safety to the off-safe position, restrain the hammer, pull the trigger, and ease the hammer down to the fired position. Place a thumb on top of the twin hammer springs to restrain them, and push out the hammer pivot pin toward the left.

13. Move the hammer upward until its spring base pin climbs over the edge of the front projection of the guard unit, relieving the spring tension. Remove the hammer, springs, and guides upward. The spring system is easily removed from the hammer.

14. Removal of the hammer pivot pin will have freed the shell stop spring. Insert a small screwdriver to lift it out upward, and remove it.

15. Remove the cross pin that is the rear base for the twin hammer springs toward either side.

16. Drift out the small cross pin at the upper front of the trigger group, using a punch of very small diameter. Restrain the carrier latch assembly as the pin is removed.

17. Remove the carrier latch assembly, and its spring and plunger, toward the front. The carrier latch trip can be separated from the latch by drifting out its small cross pin.

18. Removal of the carrier latch will give access to the shell stop pin. Use an angled punch at the front to push out the pin toward the left. The shell stop will not be freed for removal. See the next step.

19. Using a very small punch, drift the shell stop limit pin inward, and remove it from the carrier latch spring recess.

20. Remove the shell stop toward the front.

21. Drift the trigger shield cross pin toward the right, just far enough to clear the rear of the shield.

22. Remove the trigger shield upward.

23. Insert a screwdriver, angled from the rear, to pry the tip of the disconnector spring downward, out of its recess in the underside of the disconnector. Caution: Hold a fingertip on the left side to restrain the spring and plunger as it clears, and ease them off upward.

24. Push out the trigger pin, and remove the trigger and disconnector assembly upward. Drifting out the cross pin will allow separation of the disconnector from the trigger, but the pin is riveted in place, and should be removed only for repair.

25. Drift out the sear pin, and remove the sear upward.

26. Drift the roll pin at the rear of the housing further toward the right, and insert a small screwdriver from the left to lift the safety spring and its plunger out upward.

27. Remove the safety button toward either side.

28. Grip the action bar assembly, and move it slightly toward the rear. Grasp the operating handle firmly, and pull it straight out toward the right.

29. Insert a fingertip in the bottom of the receiver to depress the cartridge stop on the underside of the bolt, and slowly release the spring tension, moving the action bar and bolt assembly out to-ward the front.

30. Even after the bolt is moved out, the recoil spring is still under tension, so control it and ease it off the magazine tube. Detach the bolt from the action bars, tipping it toward the left to disengage it.

31. Remove the bolt slide from the underside of the bolt. Drifting out the cross pin in the slide will allow removal of the shell stop and its spring. Note that the spring is a torsion type, and is under tension, so restrain it as the pin is drifted out toward the right. The bolt handle retaining plunger and spring can also be removed by drifting out the cross pin at the front of the slide.

32. Drift out the cross pin at the upper rear of the bolt, and take out the firing pin bushing, firing pin, and return spring toward the rear.

33. After the firing pin assembly is removed, take out the locking block downward.

34. Insert a small screwdriver between the extractor and its plunger, depress the plunger toward the rear, and lift the extractor out of its recess. Caution: Control the plunger, ease it out, and remove the plunger and spring toward the front.

35. The carrier release, which is tempered to be its own spring, lies in a recess on the inside of the right receiver wall, and is retained by a vertical pin at the rear. Use a roll pin punch to drift the pin upward (it is replaced in the same direction), and remove the carrier release.

36. Insert a tool from the front to restrain the magazine end piece, and push out the vertical pin in the magazine tubs, just behind the gas piston area. Slowly release the spring tension, and remove the end piece, magazine spring, and follower toward the front.

37. Remove the bultplate, and use a B-Square slock i tool or a long-shanked screwdriver to back out the stock bolt and its washer. Take off the stock toward the rear. Removal of the stock bolt will also free a nylon buffer, inside the rear of the receiver, and this can be pried out toward the front if necessary. A steel barrel guide is mounted inside the top of the receiver, staked in place, and this is not removed in normal takedown.

Reassembly Tips:

1. When driving the large roll pin at the rear of the trigger housing across toward the left, insert a tool to depress the top of the safety spring as the tip of the pin passes.

2. When replacing the hammer and hammer spring assembly, turn the rear spring base cross pin so the holes are oriented upward. Set the rear tips of the spring guides against the bar, and press the assembly downward until the tips enter the holes in the pin. Then, swing the assembly over toward the front to rest against the front shelf of the housing, holding it in place tor reinsertion of the hammer pivot pin.

3. When reassembling the hammer pivot pin, insert a small tool on the left side to depress the shell stop spring as the tip of the pin passes.

4. When reassembling the gas piston system, refer to steps 2 through 6 for the proper arrangement of these parts. When replacing the gas cylinder plug on the stem of the piston valve at the front, note that its concave surface goes toward the rear.