Barrels to Match Magazine Tube Lenth

[tihshho]

So I wasn't sure the section to post this. I was able to get my hands on an 870 express receiver so I could tinker around and build an 870 to my expectations.

Since the receiver was sold as a receiver with brazed magazine tube, bolt (new firing pin, firing pin spring, non MIM extractor and polished old style bolt), ejector spring, slide assembly, left and right shell latches, and receiver stud I didn't have much to go on to date the receiver. Seems like I'll need the original barrel to do that, which I don't have neither did the seller. I've put together a parts list as I'd like to build a spec'd out express tactical to replace my Mossberg 500, but the problem I'm running into is barrel options. I'd like to go with an 18.5" barrel, but I prefer going with something with interchangeable chokes so I can bring it to the range and play around with it without having to keep a home defense barrel sitting at home and whatever barrel(s) coming with me to the range. The barrels I've been looking at seem to have different placed lugs to where the barrel mates to the magazine tube. Most 18.5" barrels seem to fit receivers with the shorter tubes and the receiver I have has what I believe to be a 5 shot tube (12.25") and I'm not sure which barrels are suited to mate up with that tube. Anyone have a list of barrels in the 18/18.5/20" range that would fit?

I've seen some people place CPVC sleeves over their magazine tubes, but the engineer in me doesn't like the idea.

[Synchronizor]

You can date your gun using the serial number on the receiver, though you'll have to contact Remington to get a precise date. Publicly-available information can only give you a general range of years from the serial number.

Barrels are pretty simple for the 870. Ever since the 870's introduction in 1950, nearly all 12ga guns have used the standard-size magazine tube, which holds four typical 12ga shells (though this capacity can vary with very long or short shells). These magazine tubes should be just under 11.5" in length, as measured from the front of the receiver. Any standard 12ga barrel should fit any standard 12ga receiver regardless of length, finish, year, or chamber size; so the options are too numerous to list. There are 18 - 20" Rem Choke barrels available with a variety of different sights, and you can always have a fixed-choke barrel threaded for interchangeable choke tubes if desired.

There have also been non-standard 12ga receivers with 3- or 6-round magazine tubes (plus, 870 clones often use 5-round tubes). Receivers with 3-round tubes and barrels to match are not common, the only examples currently in production are special combat 870s that're only marketed to military & LE. 6-round magazine tubes are used on a number of recent Express Tactical receivers. The only barrels made to fit these special receivers are 18.5" in length, so they're quite easy to recognize because their guide rings are just a couple inches back from their muzzles.

If this is going to be a home defense gun, I would highly recommend replacing your old-style bolt with a new-style one, and making sure your other action parts are up-to-date as well. The older-style parts are acceptable in a sporting or recreational gun, but because they can lead to action jams in certain circumstances, you don't want them in something your life may depend upon.

[tihshho]

Thanks Synchronizor for all of that info. For some reason and lots of reading of threads on various sites it came off as if barrels were going to be a troublesome part, but your input makes it sound a lot more simple. I'm probably going to get a simple bead site 18.5" from an express tactical if I can find it. I'd like to go with an OEM barrel as then I know for fact they are setup for Remchoke and I don't have to ship out a barrel to a gunsmith.

I just picked up a few things for the setup today to get things going:

1 - Forend Tube Assembly (Remington)
2 - Forend Tube Nut (Remington)
3 - Stock Bearing Plate (Remington)
4 - Spring and follower for stock mag tube (Scattergun Technologies) - Will be upgrading them later on for a tube extension and putting these into my other Express
5 - Forend and Stock (Hogue) - Figured I'd try them
6 - Anti-Walk Trigger Pins (Mesa Tactical) - Figured I'd try them
7 - Police Trigger Plate Assembly (Remington)
8 - Stock Bolt (Remington) - Just found out I didn't need this as Hogue's stock has it's own bolt...
9 - Stock Bolt Lock Washer (Remington) - Not sure if I'll need this yet
10 - Police Magazine Cap (Remington) - Temporary until I put on a mag extension

As my current 870 Express barrel fits I'm going to put it through it's paces as soon as I can get to the range and then order the 18.5" barrel.

[Synchronizor]

You shouldn't need the stock bearing plate if you're using a plastic Hogue stock. Those bearing plates are used with wood stocks to distribute force better & avoid cracking. Synthetic stocks have different material properties, and don't require that support.

[tihshho]

Well crap, haha. Guess I have another part to build another 870. Want to build a slug setup later on, so I probably will go with a woodstock for it. Or if I can find an older thick frame 20 gauge I'll build it up for the misses.

[tihshho]

Not exactly related, but I didn't want to start a new thread on this. Parts came in and I got everything together with what came in and lets just say there was a moment that was a total bummer... I go to mount the slide block to the new OEM Remington slide assembly tube rails and guess what... Slide block is too old for the modern set of rails! Here are some pics for reference off of the web:

Old Style:


New Style:


If you look on the right edge of the bolt you will notice a notch that rides in the slide assembly rails on the newer model. Mine does not have that, and compared to the old model pics I have above, mine doesn't even have the bevel on the front side (left/right) rails.

[Synchronizor]

Yeah, along with the bolt & carrier, Remington changed the 870's slide assembly as part of the flex-tab update. A new-style slide assembly will fit in old-style action bars, but not the other way around.

I assume you knew you needed a new-style slide assembly. Did someone send you the wrong part?

[tihshho]

I actually knew nothing about the slide block having multiple versions along with the slide assembly tube. I was hoping to have a functional setup minus the barrel (so I could work with the action and break it in with my 28" barrel), but it doesn't seem like that will be the case.

I've send something off to Remington as a technical question as I'm unsure, but I'm curious if the slide blocks are interchangeable with bolts? The reason I ask is not to avoid getting a new bolt, but to delay it. Again, I have the old style bolt that is not flextab, but if I order a new slide block with the barrel I'm good to go for a functional shotgun to break in. At that point it would be a plinker and far from a reliable home defense setup, but I'm not trying to rush into the home defense side. Besides that I would like to use the shotgun for 3 gun so I really get to know my way around the setup, rather than have a shotgun that collects dust and is occasionally shot for practice.

Goals next week are to order the barrel, magazine extension, and slide block if it works with the old bolt. If not I'll be replacing the mag extension with the bolt in said order. After that I plan to upgrade the safety to a large button, most likely a Vang, and find a rail that fits the holes a previous shop drilled and tapped for one of the previous owners setups so I can red dot it.

[Synchronizor]

Any combination of old- or new-style carrier, breech bolt, and slide assembly from 12ga 870 magnum or non-magnum sotguns should work together (aside from the anti-jam feature), provided of course you have a slide assembly and fore-end tube assembly that fit together (new/new, new/old, or old/old will work, but new/new is obviously ideal).

[tihshho]

I hope I'll have some time tomorrow to post up some pics after the assembly is complete. Everything for the first iteration of this 870 should be here:

- Express Receiver
- Tactical 18.5" Threaded Barrel <<Last part I'm waiting on arriving
- Police Trigger Assembly
- Police Barrel Nut
- Slide Assembly
- Flex Tab Slide Block
- Scattergun Technologies Spring & Follower
- Hogue Overmold Stock and Forend
- Mesa Tactical Receiver Pins

I plan to do some further upgrades on this that are minor but either promote better performance or additional functionality.

Iteration 2:

- Flex Tab Bolt
- Nordic Components +2 Extension
- Nordic Components Extension Barrel Clamp