How To Take Apart A Remington 870: The Ultimate Field Stripping And Maintenance Guide

Mastering the disassembly of a Remington 870 involves a systematic five-stage process: clearing the chamber, removing the barrel via the magazine cap, punching the trigger plate pins, and extracting the bolt assembly through the receiver. This procedure ensures internal components are accessible for cleaning and inspection while maintaining the structural integrity of the pump-action mechanism.

Essential Gear and Safety Protocols for Shotgun Disassembly

Before engaging with the mechanical components of the Remington 870, establishing a controlled environment is paramount. This shotgun, while legendary for its durability, relies on precise tolerances and specific spring tensions that can cause components to launch if not handled with care. The disassembly process generally falls into two categories: field stripping (removing the barrel, trigger group, and bolt) and detail stripping (disassembling the bolt itself and the magazine tube). For most maintenance cycles, field stripping is sufficient.

The following list outlines the requirements for a successful disassembly and deep clean:

• Mandatory Safety Gear: Eye protection is non-negotiable due to the high-tension magazine spring and the potential for solvent splashback.
• Essential Hand Tools: A 3/16-inch steel punch or a specialized brass drift punch is required for the trigger plate pins. A small nylon or rubber mallet helps provide controlled kinetic force for stubborn pins.
• Work Surface: A padded gun mat or a clean, non-slip workbench prevents marring the finish on the receiver or the vent rib of the barrel.
• Cleaning Supplies: High-quality CLP (Cleaner, Lubricant, Preservative), a 12-gauge bore snake or cleaning rod with bronze brushes, and lint-free cotton patches.
• Prerequisite Knowledge: Users must understand the "condition check" protocol to ensure the firearm is completely inert before tools touch the chassis.
• Duration and Budget: A standard field strip takes 5 to 10 minutes, while a thorough deep clean requires 30 to 45 minutes. Budgeting for basic tools typically costs under $50.

The Definitive Sequence for Field Stripping the Remington 870

The Remington 870 utilizes a bottom-loading, side-ejecting receiver design. The disassembly must follow a specific order of operations to prevent damage to the shell latches and the action bars.

Step 1: Establishing a Cold Weapon and Safety Clearance

Safety is the foundational step of all firearm maintenance. You must verify that no ammunition is present in the chamber or the magazine tube.

1. Point the shotgun in a safe direction with your finger off the trigger.
2. Depress the action bar lock (located at the front of the trigger guard) and slide the forend halfway back.
3. Visually and physically inspect the chamber for a shell.
4. Inspect the magazine tube by looking at the follower through the loading port.
5. Cycle the action several times to ensure the elevator and extractor are clear.
6. Once confirmed clear, leave the bolt in the forward (locked) position.

Warning: Never attempt to disassemble a firearm with a closed action unless you have verified it is empty. Failure to do so can result in accidental discharge during the removal of the trigger group.

Step 2: Removing the Magazine Cap and Barrel

The barrel is held in place by the magazine cap or a magazine extension nut. This component applies tension to the barrel lug, securing it against the receiver.

1. Unscrew the magazine cap by turning it counter-clockwise. If you have a magazine extension, be aware that the magazine spring is under significant tension and may fly out once the nut is loosened.
2. If your 870 is an Express model with a plastic spring retainer, use a flat-head screwdriver to slightly depress and turn the retainer until it clears the dimples in the magazine tube.
3. With the magazine cap removed, grasp the barrel and pull it forward, away from the receiver. It should slide out easily.
4. Set the barrel aside on a protected surface to prevent damage to the front bead or the ejector located inside the barrel extension.

Step 3: Extracting the Trigger Plate Assembly

The trigger group is a self-contained unit held in place by two cross-pins located in the receiver.

1. Lay the receiver on its side on the padded mat.
2. Position your 3/16-inch punch on the rear trigger plate pin. Use the mallet to tap the pin through the receiver.
3. Repeat this process for the front trigger plate pin. Note that on some older models, these pins may have different lengths or retention springs; keep them organized.
4. Once the pins are removed, lift the trigger plate assembly upward and out of the receiver.
5. Inspect the assembly for debris. Do not further disassemble the trigger group unless you are a qualified gunsmith, as the internal springs and sears are difficult to re-seat without specialized jigs.

Pro-Tip: If the pins are difficult to move, ensure the action bar lock is not providing lateral tension. Sometimes wiggling the trigger guard slightly while tapping the punch helps the pins clear the internal spring detents.

Step 4: Removing the Forend, Action Bars, and Bolt Assembly

This is the most technical stage of the process, as it involves navigating the internal shell latches that reside inside the receiver walls.

1. Reach inside the bottom of the receiver. There are two long metal strips on either side—the left and right shell latches.
2. The right shell latch (on the ejection port side) must be depressed against the receiver wall to allow the action bars to slide forward.
3. Simultaneously, you may need to depress the left shell latch.
4. Slide the forend assembly forward and off the magazine tube.
5. As the forend moves forward, the bolt and the bolt slide (the flat metal piece the bolt sits on) will come out of the receiver.
6. Be prepared to catch the bolt and slide, as they are not mechanically attached to the action bars and will fall off once they clear the receiver.

Step 5: Disassembling the Bolt and Firing Pin

For a deep clean, you should separate the bolt from the slide and inspect the firing pin.

1. Lift the bolt body off the bolt slide.
2. Inspect the firing pin at the rear of the bolt. On the 870, the firing pin is held by a transverse pin.
3. Unless the firing pin is broken or excessively filthy, do not remove it during a standard field strip. Simply spray the bolt with CLP and use compressed air to blow out any carbon buildup from the firing pin channel.
4. Check the extractor hook for chips or excessive wear. This is a common point of failure that leads to extraction issues.

Comparative Specifications Across the Remington 870 Platform

The Remington 870 has been produced in several variations since 1950. Understanding the nuances between these models is vital for sourcing the correct replacement parts during your disassembly and inspection.

Resolving Common Mechanical Hurdles During Disassembly

Even for experienced owners, the Remington 870 can present specific mechanical challenges during the teardown process. These are usually related to the age of the firearm or the accumulation of carbon "sludge."

• The Barrel is Seized to the Receiver:

  
  
  
  • Root Cause: Carbon buildup or light rust has fused the barrel extension to the receiver's interior.
  • Actionable Fix: Apply a penetrating oil (like Kroil) to the junction where the barrel meets the receiver. Let it sit for 24 hours. Use a rubber mallet to gently tap the barrel lug forward while holding the receiver steady. Never use a steel hammer directly on the barrel.

• Action Bars Will Not Slide Forward:

  
  
  
  • Root Cause: The shell latches are not being fully depressed, or the hammer in the trigger group (if not removed) is in the "up" position.
  • Actionable Fix: Ensure the trigger group is removed first. If it is already removed, use a small flat-head screwdriver to push the left shell latch (the one deeper in the receiver) firmly against the wall. The action bars require about 1/16th of an inch of clearance to pass.

• Trigger Pins Will Not Budget:

  
  
  
  • Root Cause: The detent springs inside the trigger plate are under high tension, or the pins are slightly flared from previous improper tool use.
  • Actionable Fix: Apply a drop of oil to the pins. Use a starter punch (a shorter, thicker punch) to break the initial friction before switching to a standard 3/16" drift punch. Ensure the receiver is properly supported on a bench block with a hole for the pin to drop into.

• Shell Latches Fall Out of the Receiver:

  
  
  
  • Root Cause: These are "staked" into the receiver at the factory, but over time, the staking can fail.
  • Actionable Fix: This is a common occurrence on older 870s. The latches do not need to be permanently re-staked to function; they are held in place by the trigger group once reassembled. Simply align them back into their slots during reassembly and hold them with your fingers while sliding the trigger group back in.

Frequently Asked Questions

Can I swap barrels between an 870 Express and an 870 Wingmaster?

Yes, the barrels are generally interchangeable as long as the gauges match (e.g., a 12-gauge barrel for a 12-gauge receiver). However, you must ensure the chamber length of the new barrel (e.g., 3-inch Magnum) is compatible with your receiver's ejection port and the markings on the receiver.

How often should I perform a full teardown and cleaning?

A basic barrel cleaning should happen after every trip to the range. A full field strip, including removing the trigger group and bolt, should occur every 500 to 1,000 rounds, or once a year if the shotgun is kept in a humid environment or used for hunting in inclement weather.

Why does my 870 Express have dimples in the magazine tube?

The dimples are a design choice for the Express line to retain the magazine spring using a plastic "clover-leaf" shaped retainer. If you wish to install a magazine extension, these dimples must be removed (drilled or swaged) to allow shells to pass through the transition point.

Do I need to lubricate the action bars?

Yes, but sparingly. The action bars benefit from a light coat of oil or a dry PTFE lubricant to reduce friction against the receiver walls. Over-lubricating these parts can attract dust and unburnt powder, creating a "gritty" feel in the pump action.

What is the "Flex-Tab" system in the 870?

The Flex-Tab system was an upgrade introduced to prevent a specific type of jam where a shell slips under the carrier. You can identify it by a "U" shaped cutout in the carrier (the flap that lifts shells). If your 870 has this, the disassembly process remains the same, but the reliability during high-stress cycling is significantly improved.

Maintain Your Remington 870 for Generations

Regular disassembly and maintenance are the keys to ensuring your Remington 870 remains the most reliable tool in your collection. By following these technical steps and using the correct tools, you protect the longevity and performance of this iconic American shotgun.