View Full Version : Remington 870 mag extension

October 2, 2007, 09:13 PM
I've noticed that on some pictures of remington 870's the mag extension will stick out about 1/8 to a 1/4 of an inch past the barrel while others will line up perfect or fall short. Why is this? Which brand of mag extension lines up flush with a remington 18 inch barrel? Im guessing remington?

October 2, 2007, 09:32 PM
The mag extention on my 870P looks exactly as the top shotgun in picture you posted - the gun came direct from Remington.

October 3, 2007, 06:34 PM
Look closer - the mag extensions are the same length. The bottom barrel is longer.


paul salchow
October 3, 2007, 07:31 PM
For the most part, with factory barrels the remington extension will stick out 3/4 of an inch.
Don't know why but they do, it could have been for the bayonet lug version that used the extension with a lug adaptor.
The only other extensions that we use are the Lyman ones, they sit flush with the barrels and are built very well, there easier to install than the remington for one reason, the tube is a one piece(it's all silver soldered) but because it is one piece you tighten it all the way down.
The remington is done with the nut tightened and the extension tube backed out 1/4 turn and a extension clamp needs to be used for this no matter what, if the extension tube is tightened down it will bind the mag spring and disrupt feeding.

October 3, 2007, 11:28 PM
Originally the factory extension stuck out about 1/2" to provide a mount for a bayonet mounting ring.
For reasons never stated, Remington just never bothered to alter the design.

About a year ago, Remington lengthened their shorter barrels by 1/2".
The 18" barrel is now 18 1/2", the 20" is 20 1/2".

For that reason, the extension is now about even with the muzzle.

October 10, 2007, 05:16 PM
so if i buy an 18 inch barrel from remington it will most likely really be an 18.5 inch barrel correct?

October 10, 2007, 06:33 PM

October 10, 2007, 07:32 PM
thank you very much sir

October 10, 2007, 08:14 PM
I have an older Remington Marine Magnum with the factory extension...

the extension is about 3/8" LONGER than the barrel... so, NO, Remington parts do MOT sit even or behind the muzzel...