Mossberg 590 Magazine Cap Problem

Georgian · August 5, 2011, 12:57 PM

Hey yall. I've got a Mariner 590, and I love it for the most part, except that the magazine cap is extremely tight and can only be removed with a pair of pliers (with rubber on them of course). THE THREADS ON THE MAGAZINE TUBE AND CAP ARE NOT STRIPPED OR MESSED UP! The gunsmith I spoke with told me that what it appeared to him was that the piece inside the magazine tube holding the spring down had made the end of the tube slightly expand, making the cap extremely hard to screw on and off. He said that I should file the outside of the magazine tube around the rim to make it fit better. I am skeptical about filing on something that is already thin. Do yall have any better ideas?

dswindle · August 5, 2011, 01:14 PM

Georgian,
I too live in Southeast Georgia, and I had the same problem with my Mossberg 590A1 Mariner. Your gunsmith is partially correct. The magazine retainer does cause the end of the magazine tube to expand about one-ten thousandth of an inch, but that is a good thing. If you pry out the magazine retainer you will notice that the magazine cap screws on much, much easier, but you should not leave it out although I have seen some posts on different forums that recommend doing this. The magazine tube is aluminum and the magazine cap is steel. The magazine retainer provides some needed strength to the end of the mag tube to ensure that it does not bend when screwing on the cap. After you screw the cap on and off a few times, it gets easier to replace and remove. I would recommend putting some CLP or some thin grease on the threads of the mag tube to assist in screwing in the mag cap. Again, I would not recommend that you remove the magazine spring retainer to assist in this effort.

For what it's worth, I sent my first 590A1 back to the Mossberg Repair Facility in Eagle Pass, Texas, to have it fixed for that very reason. They returned it, and it did go on a little easier, but it was still very difficult to screw on and off. I have since screwed it on and off several times, and it performs much better now. Hope this helps.

dswindle · August 5, 2011, 01:22 PM

Georgian,
I forgot to mention one other thing about this situation. If you will notice, there is a "blank space" of just a little less than one-quarter of an inch on the magazine tube before the threads begin. When you put the magazine cap on the tube, push it down first so that the threads of both the mag tube and mag cap meet. You will notice that the mag cap should be level at this point. Make sure it is level before you attempt to screw on the cap. This space is to ensure that the cap does not cross-thread with the mag tube. Again, it takes a few times before it begins to go on a little easier. You might have guessed by now that I spent some time on the telephone with a Mossberg Representative at the Eagle Pass, TX, repair facility.

August 5, 2011, 12:57 PM	#1
Georgian Senior Member Join Date: October 12, 2004 Location: SE Georgia Posts: 208	Mossberg 590 Magazine Cap Problem Hey yall. I've got a Mariner 590, and I love it for the most part, except that the magazine cap is extremely tight and can only be removed with a pair of pliers (with rubber on them of course). THE THREADS ON THE MAGAZINE TUBE AND CAP ARE NOT STRIPPED OR MESSED UP! The gunsmith I spoke with told me that what it appeared to him was that the piece inside the magazine tube holding the spring down had made the end of the tube slightly expand, making the cap extremely hard to screw on and off. He said that I should file the outside of the magazine tube around the rim to make it fit better. I am skeptical about filing on something that is already thin. Do yall have any better ideas? __________________ ~"Speak softly and carry a big stick"~T. Roosevelt God Bless

August 5, 2011, 01:14 PM	#2
dswindle Member Join Date: January 11, 2005 Posts: 55	Georgian, I too live in Southeast Georgia, and I had the same problem with my Mossberg 590A1 Mariner. Your gunsmith is partially correct. The magazine retainer does cause the end of the magazine tube to expand about one-ten thousandth of an inch, but that is a good thing. If you pry out the magazine retainer you will notice that the magazine cap screws on much, much easier, but you should not leave it out although I have seen some posts on different forums that recommend doing this. The magazine tube is aluminum and the magazine cap is steel. The magazine retainer provides some needed strength to the end of the mag tube to ensure that it does not bend when screwing on the cap. After you screw the cap on and off a few times, it gets easier to replace and remove. I would recommend putting some CLP or some thin grease on the threads of the mag tube to assist in screwing in the mag cap. Again, I would not recommend that you remove the magazine spring retainer to assist in this effort. For what it's worth, I sent my first 590A1 back to the Mossberg Repair Facility in Eagle Pass, Texas, to have it fixed for that very reason. They returned it, and it did go on a little easier, but it was still very difficult to screw on and off. I have since screwed it on and off several times, and it performs much better now. Hope this helps.

August 5, 2011, 01:22 PM	#3
dswindle Member Join Date: January 11, 2005 Posts: 55	Georgian, I forgot to mention one other thing about this situation. If you will notice, there is a "blank space" of just a little less than one-quarter of an inch on the magazine tube before the threads begin. When you put the magazine cap on the tube, push it down first so that the threads of both the mag tube and mag cap meet. You will notice that the mag cap should be level at this point. Make sure it is level before you attempt to screw on the cap. This space is to ensure that the cap does not cross-thread with the mag tube. Again, it takes a few times before it begins to go on a little easier. You might have guessed by now that I spent some time on the telephone with a Mossberg Representative at the Eagle Pass, TX, repair facility.