Rem 870 express mag tube question

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AllGrainTactical
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Rem 870 express mag tube question

Post by AllGrainTactical » Tue Jun 02, 2015 5:33 pm

I have a fairly standard 870 express 12 ga. I am turning it into a HD gun. Factory 28" barrel has been removed and replaced with an 18.5" police cylinder bore with bead. This new barrel has a ball detent in the lug. While it will secure with factory mag cap with internal ratchet teeth, I would prefer to install old type cap to work with ball detent on barrel lug. If I'm doing that I figured I might as well add a extended mag tube instead of a new cap. This leads to the mag tube dimple debacle.....I know it's beating a dead horse. I do not want to drill them or pound a socket. If I leave the dimples in, would a plus 1 tube possibly still work, my thinking is that the mag spring could still stack up behind the dimples into the plus one tube with the follower stopped at the dimples. I suppose I could just test by removing cap and loading shells into tube and see how many fit until follower stops at dimples. I'm using the s&j type 2 no jam follower. Wondering if anyone has tried this? Thanks

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Synchronizor
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Re: Rem 870 express mag tube question

Post by Synchronizor » Thu Jun 04, 2015 6:27 am

AllGrainTactical wrote:If I leave the dimples in, would a plus 1 tube possibly still work, my thinking is that the mag spring could still stack up behind the dimples into the plus one tube with the follower stopped at the dimples.
A standard 4-round 12ga 870 magazine tube gives you about 12.125" of tube space, but only about 11.25" of that is behind the dimples in tubes that have them. A tailed S&J follower would take up about .55" of that, leaving 10.7" of space for shells. If you divide 10.7 by 5, that means your shells would need to be just 2.14" long to get that capacity. That's quite a bit shorter than the crimped lengths of standard 12ga rounds (2.5" & 2.75"). If you try loading the magazine without the spring, spring retainer, & magazine cap in place, you'll see what I'm talking about. There are some 2" buckshot shells that would let your magazine hold five with the dimples intact, but those are too short to be 100% reliable in an 870.

Really, if you want extra rounds, you're going to need to remove those dimples. There are safe, effective ways to do that without compromising the gun or risking damage, including drilling them out (probably the simplest method), or swaging them flat (effective, but requires more know-how and special tools). If you're not comfortable doing those procedures yourself, a competent gunsmith should be able to do it for you.

Alternatively, just leave your gun 4+1, and spend the money you would have used on an extension on a case or two of shotshells. Several hundred rounds worth of practice time should be at least as useful as - if not more so than - an extra round or two in the magazine.

AllGrainTactical
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Re: Rem 870 express mag tube question

Post by AllGrainTactical » Mon Jun 08, 2015 3:50 am

Thank you for the info. That's about what I figured. I was just kind of curious if it was possible to get maybe one extra round even with the dimples. However looking at the math, I don't think so. Even if I ditch the spring retainer and have a short follower. As always, thank you sync for the great vids and info! Cheers

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