This post is based on a chapter from the Remington 870 Guide eBook.
The Remington 870 is easy to disassemble and reassemble; you will only need these instructions the first few times. With enough practice, you will be able to disassemble and reassemble your shotgun with your eyes closed.
You may need to disassemble your shotgun in the following cases:
• For the first cleaning of your Remington 870, due to the preservation grease, right after purchase.
• For regular cleaning and maintenance of your shotgun.
• When checking your shotgun’s barrel to see if there are any obstructions inside.
• For transportation of a shotgun, disassembled in a case or small bag.
• For storage of a shotgun, disassembled in a case or small safe.
Never forget about the safety rules when disassembling a shotgun. There are known cases when carelessness during the disassembly of a gun was the cause of accidents.
WARNING! Check the ejection port, chamber, and magazine tube to make sure that there are no shells in the shotgun prior to disassembly.
1. Engage the safety.
2. Push the action bar lock upward and pull the forend back to open the action.
Slide the forend back, approximately halfway.
3. Unscrew and remove the magazine cap (magazine extension).
If you have a magazine cap, the spring is held in place by a magazine spring retainer; if you have a magazine extension, the spring is held by the extension itself, and will fly away when the extension is removed. Be careful to hold the magazine extension firmly and decompress the magazine spring slowly.
Attention! Magazine springs are under pressure; wear eye protection
4. Take out the magazine spring retainer, magazine spring and follower.
5. Pull the barrel from the receiver.
6. Compress and hold the left shell latch.
7. Slide the forend forward and off the magazine tube. Hold the bolt and the bolt carrier, because they will fall off from the action bars.
8. Take out the bolt and bolt carrier from the rear of the action bars.
9. This step is for the Remington 870 that doesn’t have a magazine extension, with the spring kept in place by the magazine spring retainer.
Attention! The magazine spring is under pressure; wear eye protection.
Insert a flat head screwdriver into the slot in the magazine spring retainer. Push the magazine spring retainer into the magazine tube and rotate it. This will allow you to take it out.
10. Push out and remove the two pins from the receiver.
11. Take out the trigger group. If you have a pistol grip stock, you may experience a problem removing the trigger group from the receiver. There is no need to remove the stock; push the carrier forward to the magazine tube and then pull out the trigger group.
Reassembly is simple; it is the reverse process.
1. Insert the trigger group assembly into the receiver.
2. Align the trigger group with the holes in the receiver. Insert the pins and push them in.
3. Put the bolt assembly in; set it on top of the notches on the action bar assembly.
4. Slide the action bar assembly onto the magazine tube. Line it up with receiver.
5. Push the left cartridge stop, and slide the action bar assembly into the receiver.
6. Push the action bar lock upward, and pull the forend back to open the action.
7. Slide the forend forward approximately halfway.
8. Put the barrel on.
9. Put the follower and spring into the magazine tube.
10. This step is for the Remington 870 that doesn’t have the magazine extension, with the spring kept in place by the magazine spring retainer.
Install the magazine spring retainer. Insert a flat head screwdriver into the slot in the magazine spring retainer. Push the magazine spring retainer into the magazine tube and rotate it.
Remington 870 Disassembly Instructions Video:
Remington 870 Bolt Disassembly
Video which shows Remington 870 bolt disassembly and firing pin removal.
The bolt of the Remington 870 firearm is a mechanical part that is responsible for shielding the rear of the chamber when firing the weapon. That way, the propellant can burn without affecting any of the other unused shells in the magazine tube. Once the shell has been fired, the bolt moves out of the way so that a new shell can enter the chamber. This should be pretty basic knowledge to those who understand the mechanics of how a shotgun works.
When you begin to disassemble the Remington 870 bolt, you must first make sure that all the shells and ammunition have been removed from the chamber and magazine cap of your Remington 870 shotgun. This will ensure that there are no accidental firings as you proceed to disassemble it. After you have verified this, begin to disassemble your weapon by engaging the safety and then sliding the action bar lock in an upward direction. Then, pull back on the forend so that the action is open and then slide back the forend about halfway.
At this point, you will start unscrewing the magazine cap in order to remove it. Be careful that the spring doesn’t fly away after you remove the magazine cap because this can happen very easily. Just slowly decompress the magazine spring as you hold the magazine tube tightly and you shouldn’t have this problem. Next, take out the follower after you take out the magazine spring and then pull the barrel off and away from the receiver. Press down on the left shell latch with your thumb and hold it there. Slide the forend all the way forward so that it comes off the magazine tube.
Now you can begin to knock out the firing pin from the bolt. Once you have done that, take out the pin along with the retractor spring. Reverse the entire process by adding your new firing pin to the bolt and the retractor spring you previously took out. If you have a new retractor spring, then use that instead although it that shouldn’t matter. After you have gotten the firing pin and retractor spring back inside the bolt, reassemble your weapon and then test it out by firing a few rounds at a target.