View Full Version : Bought a 3 1/2 mag 870...barrel issue

Bob S
December 26, 2010, 10:55 PM
For all you shotgun experts out there:

Bought a Remington 870 supermag express in camo recently as a gift for my brother in law. Looked at the display model and everything looked great. After he opened it at Christmas, we noticed that while the reciever says 3 1/2mag, the barrel that came with it says for 2 3/4 and 3 inch shells?? Has there been some mistake, or did I get the wrong barrel with the gun? It was brand new and appeared to have come from the factory.

So the big question... is it safe to shoot 3 1/2 mag out of the barrel marked for 2 3/4 and 3 inch shells?

Thanks in advance for your help.

December 26, 2010, 11:41 PM
So the big question... is it safe to shoot 3 1/2 mag out of the barrel marked for 2 3/4 and 3 inch shells?


As for the root cause, I have no idea... But I would start by taking it back to the dealer...


December 27, 2010, 12:47 AM
Seems you have the wrong barrel, but…

First some background:
Remington 870-type guns come in 2-3/4", 3" and 3-1/2" length actions, and generally the barrels are interchangeable.
Rule #1 Don't use a cartridge longer than the is marked on the barrel!
Rule #2 The length of the action will determine the maximum shell length cyclable.

Possible misfits:
•Barrel's chamber shorter than the action
A 2-3/4" barrel on a 3" frame works fine with 2-3/4" shells; but, if you cycle 3" into the shorter chambers, you're courting disaster. Although a gun in this configuration works fine as long as you use the shorter shells, there is a potential danger if you stuff longer shells into the short barrel.

•Barrel's chamber longer than the action
A 3" barrel fits fine in a 2-3/4" with not problems; but, you can only cycle 2-3/4" shells. This configuration doesn't pose a safety problem. Remington used to sell 2-3/4" and 3" barrels separately, but now sells 3" chamber barrels for both 2-3/4" and 3" chambered 12-ga 870 guns. Some folks mistakenly think this makes there old 2-3/4" long action into a 3" -- not so.Remington's extra barrel data page contains:
NOTE: Model 870 Extra Barrels with 3" chambers will fit Super Magnum, Magnum, and 2-3/4" receivers. These barrels will handle both 2-3/4" and 3" shells when used on Magnum receivers. Use only 2-3/4" shells when these barrels are used on 2-3/4" receivers.

It seems your brother-in-law's gift is a strange set up; but, it isn't necessarily the wrong barrel. Perhaps Remington is marketing a standard barrel on a Super-mag action; but, I'd think their legal department would object. Before contacting Remington, check the gun's model number (found on the box) on the Remington web site -- I suspect you'll find it's the wrong barrel, or it's an off-catalog item.
Brent is correct,
Do no use 3-1/2" shells in a barrel marked for 2-1/2" & 3" shells.

May 30, 2013, 11:27 PM
Not having a Remington 870 Super Mag I cannot compare receivers and barrels between the 870 Magnum and Super Magnum.

I have a Remington 870 Magnum (Turkey Special) with a 22" barrel. I used it last year during dove season on some off days and enjoyed using the pump action. I want to get either a 26" or 28" 870 Express barrel for dove season this year and wanted to ask if the "Super Mag" barrel would both fit the regular 3" Magnum receiver and not have any drawbacks. The reason is that I am looking for a used barrel and if a Super Mag barrel comes along I wanted to know if this is a viable option.

In addition to whether it will fit the Magnum receiver, if it will, does anyone have any input as to whether the longer chamber would have a notable impact on accuracy?

Hate to revive an old thread but the answer to my question should complement the thread. Thanks for any input.

May 31, 2013, 12:53 AM
Yes, you can run a 3 1/2" barrel on your standard 870, Remington actually ships some models that way. Some folks claim that they don't perform as well, especially with 2 3/4 shells but I haven't seen any hard evidence of that.

June 2, 2013, 11:01 PM
I have a supermag that I bought ages ago and use a 3" marked slug barrel on it, and a 3" marked 22" barrel. But, if you use that 3" marked barrel with 3.5" shells it wont work well. Extraction will be awful until it eventually ruins it. I would say factory mix up. DONT USE IT!

June 3, 2013, 08:28 AM
My 870 is marked MAGNUM EXPRESS but does not have a shell length marked on it. I have been told it will accept 3 1/2" shells but I am reluctant to try them. In fact I don't want to shoot 3 1/2 inchers so I'm safe but what do I tell a potential buyer if I sell?

June 3, 2013, 07:20 PM
I sure hope the OP resolved his issue 2-1/2 years ago.
Forget the rollmarking. If your serial nuber ends in 'M' it is a Magnum receiver, for 3" shells max. If the serial number ends in 'A' it is a SuperMag for 3-1/2" shells. Anything is possible with rollmarking, but I have not seen a SuperMag receiver that did not say SuperMag on it.

June 4, 2013, 12:41 AM
Thanks for the information. If a SuperMag RemChoke barrel comes up for auction and sells for under $100 I know now it will lock up with my Magnum receiver/bolt.

June 4, 2013, 06:38 AM
But, if you use that 3" marked barrel with 3.5" shells it wont work well. Extraction will be awful until it eventually ruins it. I would say factory mix up. DONT USE IT!

Well, DUH! You are trying to put 10# of stuff in a 5# bag.....all while taking a chance on the gun blowing up (which would earn you the Darwin award for the week)

June 5, 2013, 01:20 PM
@damo...extraction would be my least concern...the crimp would probably be blown off of the hull considering it would be resting on the 3" forcing cone.( which could and probably would cause severe consequences) A 3.5 will chamber in a 3. The hull isn't measured crimped. Its measured open.