Remington 870 Tactical Shotgun Build

 

Tactical Remington 870 Build

UPDATE: To improve patterning, see our post on lengthening the forcing cone and back boring here

UPDATE: Scattergun Technologies Trak-Lock II Sight Installation is here

UPDATE: Vang Comp Systems ghost ring sight installation is here

Rifleshooter.com and Brownells team up to rebuild a neglected 870 express into a top tier defensive shotgun

Editors Note: The following documents a Remington 870 conversion and is presented for information purposes only.  

Editors Note: Wear appropriate eye protection when working with tools.

Brownells provided the following tools and parts for this project:

Introduction

I have been an Remington 870 guy since I was 18-years old.  I had been saving up and finally bought a Remington 870 “Police Magnum” with top folding stock from my local dealer.  The 20-inch barrel with rifle sights were complimented nicely by the extended eight shot magazine and corn cob forearm.  My friend bought the exact same model, we had exquisite taste.

I remember the first time I shot it like it was yesterday.  At the time, the stamped metal folding stocking without a recoil pad and long length of pull seemed cool.  My buddy and I enjoyed bruised shoulders and cheeks.  We looked forward to saving up enough money to buy a case of cheap bird shot and heading out to the sand pit to shoot 250-rounds at a time.

Times have changed, I still own the same gun, however, it looks very different.  The stock has been replaced with a standard fiberglass model.  The 20-inch rifle sight barrel has been cut and crowned to 18.5″ and a set of ghost ring sights has been installed.  The gun shoots better and is a pleasure to own, but I held onto that folding stock and still pull it out from time to time.

If you stop by your dealer and price out an 870 today, you will be impressed with the wide range of models available.  The 870 Wingmasters, Police, Express and Express Tactical models make for an expansive line up.  You will also notice the relatively high premiums commanded by the Police guns.  These guns come off of a separate assembly line, use bar stock parts and are subject to extensive quality control inspections.

A while ago, I figured out it was cheaper and far more interesting to buy used 870s and rebuild them.   Sometimes I buy police department trade-ins from various online dealers, but the supply is intermittent.   Lacking patience, I also check local dealers looking for guns in poor condition for a fair price.  Recently I found one.

If you never rebuilt or customized a firearm, a shotgun is a great place to start.  Most of the upgrades are fairly simple to perform and cost less the tricking out an AR15.

Base gun

Our base gun for this build is a Remington 870 Express built in 2006 with a wood stock set.  This gun has a plastic trigger housing and the now discontinued “J-Lock” internal locking mechanism safety.  The magazine tube is not dimpled, and shows evidence that the previous owner must not have been very sophisticated, the base of the magazine extension is covered in gouges where he tried to tighten it with pliers.  Mechanically the gun appears to be in good condition. I paid $160 for the gun.

This is the project gun, a 2006 Remington 870 Express.  Note the black plastic clamp to mount a laser on the front.

The lack of wear on the bolt finish indicates this gun was not shot a lot.  However, the bolt face indicates it was test fired.

The knurling was damaged with pliers by the previous owner

Initial Disassembly

You need the right tools to complete the job, this is especially true when working on firearms.  For this project I will be using the Remington 870 Service Kit from Brownells.  This kit contains everything the professional gunsmith, armorer. or serious hobbyist needs to disassemble, maintain, repair and reassemble a Remington 870 shotgun.  A complete listing of what is included in the kit is available here.

Have a storage plan in place before starting firearm disassembly.  Firearms are loaded with small pins, bearings, detents and springs.  Replacing lost parts is an expensive and time consuming process.  Use a plastic storage container and small parts bags to keep track of parts as they come off the gun.  If the plan is to replace a part during the rebuild, stow it in a separate area.

The build begins by ensuring the shotgun is safe and empty.

I remove the magazine tube, spring and follower.

The factory Remington magazine tubes are secured to the barrel via a clamp.  Once this clamp is removed you can unscrew the magazine extension and remove the follower.  Since I am replacing these parts, I will store them in a separate location. With the magazine tube removed, I open the action slightly and remove the barrel.

Next, I remove the slide and bolt assemblies by depressing the shell stop.   Shown in next photo.

Using the fore end wrench from the service kit, I unscrew the nut that holds the wooden forearm in place.

Then I screw the nut back onto the slide assembly so it isn’t misplaced.

Using a screw driver remove the two screws securing the recoil pad to the stock.

Then use the butt stock bolt wrench to remove the screw attaching the stock to the receiver.

This is the socket for the stock dis-assembly tool in the Brownells 870 Service Kit.  It makes disassembly and reassembly a breeze, far easier then a screwdriver.

If you are removing a wooden stock you will notice a small metal plate in between the stock and receiver.  This prevents the stock from splitting under recoil, it will not fit in place with many new synthetic stocks.  Secure the loose pieces.  Reattached the recoil pad to the stock so you don’t lose it.  If you are not reusing the stock screw, leave that in the stock as well so it isn’t misplaced

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Using a punch, I remove the two pins from the shell plate assembly and remove the shell plate.

The gun is now disassembled.

Sight selection and installation

Most shotguns are equipped with either a basic bead (like ours when we started), rifle, or ghost ring sights.  Beads are fast but  lack accuracy.  Rifle sights are far more accurate, but many shooters find them slow.  Ghost ring sights give you the best of both worlds.

In the past I have used Scattergun Technologies and Trijicon ghost ring sight sets.  UPDATE: Scattergun Technologies Trak-Lock II Sight Installation is here  They are nice, simple, and easy to install.  They do have some critics though. One of the criticisms of the Scattergun Technologies Sights is the attachment method of the front sight.  The front sight is epoxied over the bead base and then cross pinned via a 1/16″ roll pin drill through the sides of the sight and the base.  I have found this to be a satisfactory system and have never had one come apart.  I recently tried to remove a front sight from a gun Scattergun Technologies built in the mid 90s, after I drifted the pin, I hit the front sight with a hammer- it didn’t move.  I guess it is good to periodically try new things, for this build I selected Sage Ghost Ring sights.

On the Sage sights, both the front and rear sage sights are winged, unlike the Scattergun Tech.  The front sight is solid metal.  The tube at the base of the front sight is forced over the barrel and then set with a screw.  This is a robust method of attachment.   The rear sight, as with most systems, is secured to the receiver via two screws.  Overall the sights appear more rugged then the Scattergun Technologies.  The set shown also has a tritium insert in the front sight for low-light use.  Note, you must measure the diameter of your barrel to select the proper sight set from Sage, they are press fit as well as screwed in place.

Sage Ghost Ring Sights do NOT come with installation instructions.  No problem, who reads instructions anyway. For this installation I am using a small milling machine.  A drill press and vice would work fine as well. The Sage sights require the installer to drill and tap three holes.  One to secure the front sight assembly and two to secure the rear sight assembly.

Let’s start with the front sight.  I begin by measuring from the front of the sight assembly to the center of the threaded hole used to secure it.  Once I have determined that distance I mark the barrel and head over to the mill.

I use a countersink and piece of card stock to find the center of the barrel.  When the card stock is level, I am in the center.  Note I am securing the barrel in the vice with some barrel blocks, they are designed for an AR 15 but work perfect for an 870 (795-015-100).

Next, I align the top of the bead with the countersink to make sure the barrel is vertical.

I use the countersink to start the #29 drill for the 8-32 tap.

Then drill the hole.

Now I need to remove the bead base.  You could grind, sand, or heat it off.   Over the years I have found a file is the easiest.  Take your time and be careful not to remove material in front of the base.  Since the sight is pressed over, any flat spots on the crown will be visible when installation is complete.

Next, I use the nylon hammer from my service kit and start to push the front sight into place.  Note:  I did not use oil on the mating surfaces because I plan on refinishing the gun.  Any trapped oil will become a problem during the refinishing process.

I use an 8-32 tap to thread the barrel

Now that the front sight is done, I can start on the rear.  I begin by locating the front (8-32) hole for the sight.  Since the sights do not come with installation instructions, I positioned the rear sight as far back as possible on the flat part of the receiver and center punched the front hole.

I then tap the 8-32 hole while the receiver in still on the mill.  Once this is done, I attach the rear sight wings and locate the rear, 6-40 hole.

To cut screws to length I use a screw cutting fixture.  The one I have didn’t have an 8-32 hole, so I made one from some scrap stock.  This photo shows the screw cutting fixture for the 6-40 screw.  It is hardened steel so you can file against it.

I use blue Loctite in the stick form.   I find the stick way easier to use then the liquid.

Once the screws are trimmed so they don’t interfere with the action, I attached the rear sight to the receiver.

Upgrading MIM Parts

The extractor on this Remington 870 Express is MIM.  While many find MIM parts serviceable, I have decided to proceed on the side of caution and replace the MIM extractor with a bar stock part (767-161-760).  I will also change the extractor spring ( 767-174-330) and plunger (767-174-320) while the gun is apart.

Stock Selection

For this build, I selected a Speedfeed short stock with a ribbed forearm.  Over the years, I have found this combination to be especially fast handling.  This stock has a longer length of pull then the short Hogue overmolded entry stock.  While the Hogue stocks are perfectly serviceable, the Speedfeedand has a solid construction with an excellent rubber recoil pad.

To install the stock, you simply reverse the disassembly process from earlier.

It is time to start putting the gun back together.  Since the barrel is already on the receiver, I  assemble the bolt and place it on the slide assembly.

Magazine extension

For this project we are using a Scattergun Technologies 2 shot magazine extension (800-730-080).  The kit includes the extension with sling attachment, follower, and magazine spring.

Shell Plate

The trigger guard assembly is known as the shell plate.  This gun had a plastic assembly, with weaker, Express springs.  I would rather have a metal part with the stronger and no MIM parts.  Brownells catalogs an entire Police model shell plate assembly shown below.  Part number is 767-000-501.

Safety I prefer an oversize safety on my shotguns.    Changing them out is easy.  I am using a Scattergun Technologies here (800-100-002)

To reinstall the trigger guard I use the slave pin from my service kit to align the holes.

All done, this gun handles like a dream.  With the addition of a VTAC sling, it is ready for duty.  Next stop for this bad boy is the range and a refinish.

Parts List

Overview of the parts and tools we used in our build, we have provided Brownells parts numbers and a link to each part to make replicating your build easy.