Difference in 870 mag tubes

[jbur88]

So I recently purchased a brand new Remington 870 tactical, the model with the XS ghost ring sights, 6 round mag tube and door breach choke.

link of one i bought:
https://nwarmory.com/p-54879-remington- ... 81198.aspx

I noticed the mag tube is different then the regular 870 express with the 6 round mag tube.

link:
https://nwarmory.com/p-52847-remington- ... 25077.aspx

what confuses me is that they both hold 6 rounds but the regular express mag tub appears to be shorter. The tactical model, the mag tube goes to the end of the barrel. How come they both hold 6 rounds? it would seem the tactical should hold 7 rounds based on the length of the mag tube.

[Synchronizor]

Standard 12ga 870s have a 4-round base mag tube that ends just ahead of where the fore-end stops when the gun's action is closed. There's usually a magazine cap on the end that holds the barrel on, but when more capacity is needed this cap can be replaced with a magazine extension to provide extra tube space. Nearly all 12ga 870 barrels are designed to use this mag tube length, and this enables the barrel interchangeability that makes an 870 such a versatile shotgun.

In recent years though, Remington has built some of their 18.5" Tactical models on special receivers that have a lengthened 6-round base mag tube. Everything works the same way, but the end of the mag tube and the location of the barrel guide ring are moved several inches forward. This lets the mag tube hold 6 rounds without a separate magazine extension. The gun is therefore simpler, lighter, and easier to maintain than a comparable build that uses a 4-round mag tube with a +2 extension. There's also no possibility of shells or the follower hanging up at the joint between a mag tube & extension, which can be an issue with some extensions due to poorly-matched parts, bad design, or improper installation. However, these receivers are unable to accept other 12ga barrels, since their guide rings are too far back for the extended tube. You can use a spacer or have a gunsmith move a barrel's guide ring, but really, these guns are meant to be dedicated fighting shotguns, not something you can switch barrels on and go hunting or clay-shooting.



A few specialty 870 receivers use 3-round base magazine tubes, but these are not commonly encountered in your typical gun shop or online retailer. Many 870 clones have 5-round mag tubes, and some custom shorty builds have 2-round tubes. Any of these can accept magazine extensions, but barrel choices are very limited.

what confuses me is that they both hold 6 rounds but the regular express mag tub appears to be shorter. The tactical model, the mag tube goes to the end of the barrel. How come they both hold 6 rounds? it would seem the tactical should hold 7 rounds based on the length of the mag tube.

The factory +2 mag extensions are an old military design that prioritizes reliability and service life over maximum capacity. Due to a spring with a long solid length and a built-in follower stop to prevent over-compression of the spring, there is only enough added tube space for two more typical 2.75" shells, for a total of six. Some aftermarket +2 extension kits that don't have follower stops can allow you to fit seven total 2.75" rounds under an 18.5" barrel if the tube, spring, and follower are space-efficient enough. The S&J Hardware +2 kit is one that'll do this right out of the box. Other kits may require modification or replacement of the spring and/or follower.

[jbur88]

So when you said this,

"The factory +2 mag extensions are an old military design that prioritizes reliability and service life over maximum capacity. Due to a spring with a long solid length and a built-in follower stop to prevent over-compression of the spring, there is only enough added tube space for two more typical 2.75" shells, for a total of six. Some aftermarket +2 extension kits that don't have follower stops can allow you to fit seven total 2.75" rounds under an 18.5" barrel if the tube, spring, and follower are space-efficient enough. The S&J Hardware +2 kit is one that'll do this right out of the box. Other kits may require modification or replacement of the spring and/or follower."

i think that clarify's it for me. however it was my understanding that they were both factory 2 shot extensions as Remington offered both models like that from the factory, but they look completely different. the photo you posted actually shows both guns i'm talking about. The gun on the top of the 4 round picture is the Tactical variant i have where the 6 shot mag tube goes all the way to the end of the barrel, the other factory 6 round mag tube i was referring too is the one in the photo of the 6 round gun. you can see the mag tube stops a couple inches short of the end of the barrel. yet both tubes only hold 6 rounds. So what you are saying is that the one i have on my Tactical variant is designed to last longer and be more reliable at the cost of one extra round in the tube?

[Synchronizor]

As I said, the factory +2 extension is an older military design, so it has extra features & requirements to work in. Bayonet end cap at or slightly beyond the muzzle, a system for securing a bayonet lug/sling mount against recoil & impacts, sharing a common spring with the +3 version used on 20" models, etc. The 6-round Tactical mag tubes just need enough space for two more shells, and not much more, so there's no need to stretch it all the way to the muzzle. It's also nice to have the mag cap a little further back from the muzzle, since that's where a sling would attach.

+2 is a typical, traditional capacity for fitting under a standard 18/18.5" 870. Few extensions that length actually aim for a +3 capacity boost, but some +2 setups can squeeze in 3 shells if the shells are short enough.