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Posted: 5/13/2026 8:45:19 PM EDT
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Greeting professionals. I've owned an 870 Express synthetic with a factory +2 extension since the mid 2000's. She has been my bump in the night long gun for quite some time and lives in the safe (pistol by bedside). I keep her loaded to patrol ready, with six in the tube and an empty pipe. She rarely gets shot. I recently took her out for the first time in a LONG time and put some full power loads through her and on a reload the rounds bound up terribly around the 4th or 5th shell. I chambered from where it stopped loading and fired the loaded rounds. It followed that same pattern a couple more times, and induced a couple of malfunctions while extracting and failing to chamber as well. It is now repeating with dummy rounds (both the failure to fully load and binds up trying to extract). I replaced the magazine spring with an extra power Wolff spring and just swapped the trigger assembly for a police magnum trigger group, hoping the extra power to the shell carrier would help, and the damn thing bound up again when I function tested with dummy rounds. I got five in the pipe and it stopped dead. I managed to cycle through those rounds, then it loaded fine a couple of times and repeated the malfunction. I'm getting pretty frustrated, I would like to have full faith that this thing is going to function every time, all the time when needed. I don't have any dimples in the tube, and my only assumption is it's binding at the joint/junction where the extension meets the rest of the tube? Any pointers? Upgraded follower? New extension? I'm open to any wisdom from the board. |
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Ive seen the grex leak out of rounds while in the magazine tube and when the operator had a little too much oil / gunk / rain / etc. it gums up in the magazine tube? I'm sure if you replaced the spring you cleaned the magazine tube though. Do the shells move freely when you insert them or remove them using the shell latch to remove them? (not racking it?) Follower or shell getting caught on the seam between the magazine extension? Is it screwed in all the way? Eta, the remington factory extension is actually two pieces, the tube and a collar. Not a lot of people realize that. I'll think on it. But thats what id check first. Also, your terminology is a little confusing, is the pipe the barrel or magazine tube? |
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Sorry, barrel. I don't leave one in the chamber while it's sitting in the safe. As you stated, my best guess is that the rounds or follower are getting caught on the seem. I'm reasonably sure everything is good and tight (collar and extension). As far as unloading, I haven't had any issues, the shells seem to move freely using the shell latch. |
Good, bad....I'm the guy with the gun. - Ash Williams
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Usually the 870s that came with the +2 and +3 factory extensions have that metal clip that attaches to the barrel and tube that functions as a sling attach point: Attached File There's a screw that adjusts the tension. If you screw it too tight it pulls the barrel and extension together and creates a seam where the extension screws into the connecting collar. Any chance you did that? The binding problem with tube extensions often comes from the extension not being true for one reason or another, I'd focus on making sure the extension is straight. |
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I backed that screw off a few turns and loaded/unloaded six dummy rounds a dozen times and it only felt like it THOUGHT about binding up once. That may have been the culprit. Thanks again for the advice, I'll be beating myself up for fussing with this and 'upgrading' for two months if all it took was thirty seconds and a screw driver 😡 |
Good, bad....I'm the guy with the gun. - Ash Williams
A day without a buzz is like a day that never was
Joined:
Jan 2011
Posts:
13182
EE: 100% (54)
AZ, USA
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Originally Posted By LABlackRifle: I backed that screw off a few turns and loaded/unloaded six dummy rounds a dozen times and it only felt like it THOUGHT about binding up once. That may have been the culprit. Thanks again for the advice, I'll be beating myself up for fussing with this and 'upgrading' for two months if all it took was thirty seconds and a screw driver 😡 Awesome, let us know how it turns out. |
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Is your Express magazine tube "dimpled"? If so your shell follower might be binding at the dimples as shells move from the extension tube. Bigger_Hammer 
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Originally Posted By drewski81: Dittos on the dimple at extension. Did you replace oem spring to provide for extra shell? Similar situation I experienced with same type of usage. If shell follower & spring are oem, I would start there. Also clean & oil mag tube. No dimples, I swapped out the OEM spring with an extra power in my desperation for a fix and cleaned the tube at the same time (though admittedly I didn't apply any oil). It is still the OEM follower, that was going to be my next step. I'm really hoping loosening the clamp screw does the trick, but I may swap the follower just to be extra cautious. Any recommendations for a good aftermarket option? I've seen folks recommend the S&J, but I haven't done a deep dive yet. |
Good, bad....I'm the guy with the gun. - Ash Williams
A day without a buzz is like a day that never was
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Posts:
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Originally Posted By LABlackRifle: No dimples, I swapped out the OEM spring with an extra power in my desperation for a fix and cleaned the tube at the same time (though admittedly I didn't apply any oil). It is still the OEM follower, that was going to be my next step. I'm really hoping loosening the clamp screw does the trick, but I may swap the follower just to be extra cautious. Any recommendations for a good aftermarket option? I've seen folks recommend the S&J, but I haven't done a deep dive yet. The OEM follower is as cheap as the could possibly make it, its not out of the realm of possibility that it deformed to some degree after sitting under load for some time. I bought an aluminum one off ebay, worked great but I have a Wilson Combat follower in my 870 now. I think the follower, the dog carrier spring, and the extractor claw should all be replaced on any 870 Express on general principle. But check to see if its functioning properly first before adding a bunch of new variables. |
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i just got done with a long day of teaching an armorer course, so I have updated some info on this post. Hopefully this may help. The 870 pump action has these cycles of operation: Firing Unlocking from Battery Extracting Ejecting Cocking Feeding Chambering Locking into Battery Now to break it down further: Firing Unlocking from Battery = Lose lock up, and lose lock forward Extracting = live or fired shell needs to be pulled out of the chamber as the action is moved rearward Ejecting = live or fired shell should be pushed out of the ejection port as the action is moved rearward Cocking = recocking the hammer and resetting the trigger Feeding = feeds a shell out of the magazine tube as the action is cycled rearward, then feeds the shell into the chamber as the action moves forward Chambering = shell needs to go into and fit in the chamber so the action can lock into battery Locking into Battery = Has to lock up, and lock forward So with this, can you help explain what you are exactly experiencing, which may help us diagnose the cause and find a remedy. As for shells binding in the magazine tube. Remove the magazine retaining cap, magazine spring and follower. With the magazine tube empty, point the muzzle down and insert dummy rounds or shells into the back of the magazine tube like you are normally loading it, and see if the shells go all the way foward and drop out the front end of the magazine tube, as they should and this will ensure that there is no blockage of the magazine tube. If shells bind or get stuck inside the magazine tube, then there must either be an obstruction, dent or bend to the magazine tube. Now what makes the shells come out of the magazine tube is the magazine spring pushing on the follower, which in turn pushes the shells out of the magazine tube. So make sure that shells freely move through an empty magazine tube is a simple check to see if there are problems with the magazine tube as I already mentioned. You already mentioned that you added a heavier spring, I am a huge fan of Wolff magazine tube springs for more powerful feeding. The follower could be getting stuck or dragging. This can be attributed to something with the follower like being deformed. But can also be an issue with heavy debris fouling inside the magazine tube, so you may try using one of the Brownells magazine tube brushes to swab it out. By cleaning out the magazine tube, you can eliminate that it isn't crud or fouling causing the issue. As already mentioned, make sure that your magazine tube extension isn't binging up the spring either. Next is to look at what holds and releases the shells from the magazine tube, which is the shell latches. As if you are behind the gun shooting it, there is a right and left shell latch. The left shell latch is the one that is responsible for releasing a single shell from the magazine tube as the pump action is cycled rearward. The right shell latch is what catches the second shell and holds it so it doesn't release from the magazine tube when the action is cycled rearward. So if the issue is that the left shell latch isn't moving out of the way consistently to allow a single shell to release from the magazine tube, that you need to look at the shell latch tip to make sure it is in tact. Also look at the action bar assembly, (which is the forend assembly that consists of the forend, action bars, and a spanner nut at the front that keeps things connected together. If the left shell latch isn't moving out of the way, then the left action bar may be bent and not pushing the left shell latch out of the way. The forend (front stock) could also be out of proper alignment, which is twisting the action bars and not allowing the left shell latch to move out of the way to release a shell from the magazine tube. A bent action bar will cause this issue as well (don't bend the action bars, as they are responsible for 7 out of the 8 cycles of operation. Another possible cause is that there is something going on in the left action bar channel of the receiver, that is causing left shell latch to not push out of the way, very common when someone stakes the left shell latch and accidentally pushes metal into the action bar track. If the gun had a side saddle type shell carrier added at anytime, the issue may be that whoever installed it may have over tightened the mounting screws and bent the receiver. A broken ejector tip can also be the culprit, as the front tip supports the barrel to keep it from turning inside the receiver. If broken off, the barrel can slightly twist out of alignment when cycling, and this can result a gun that sometimes feeds/locks/unlocks, and every once in a while may bind or not work correctly. So check the frong tip of your ejector and see if its damaged in any way. As for figuring out what may be the other possible issue, please try and give us a better description and we may be able to help diagnose the cause and come up with a solution. Examples would be: The shells are getting stuck coming out of the magazine tube The shells are not being lifted up by the carrier to go into the chamber Shell are getting stuck going part way into the chamber Shells are not extracting and coming out of the chamber as the action is being cycled rearward Shells are extracted out of the chamber, but they are not going out the ejection port (not ejecting) The gun will not unlock the action and go rearward after firing a live shell, but will with a dummy round CY6 Greg Sullivan "Sully" WeaponsArmorer SLR15 Rifles Defensive Edge Training (763) 712-0123 |
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Originally Posted By sully: i just got done with a long day of teaching an armorer course, so I have updated some info on this post. Hopefully this may help. The 870 pump action has these cycles of operation: Firing Unlocking from Battery Extracting Ejecting Cocking Feeding Chambering Locking into Battery Now to break it down further: Firing Unlocking from Battery = Lose lock up, and lose lock forward Extracting = live or fired shell needs to be pulled out of the chamber as the action is moved rearward Ejecting = live or fired shell should be pushed out of the ejection port as the action is moved rearward Cocking = recocking the hammer and resetting the trigger Feeding = feeds a shell out of the magazine tube as the action is cycled rearward, then feeds the shell into the chamber as the action moves forward Chambering = shell needs to go into and fit in the chamber so the action can lock into battery Locking into Battery = Has to lock up, and lock forward So with this, can you help explain what you are exactly experiencing, which may help us diagnose the cause and find a remedy. As for shells binding in the magazine tube. Remove the magazine retaining cap, magazine spring and follower. With the magazine tube empty, point the muzzle down and insert dummy rounds or shells into the back of the magazine tube like you are normally loading it, and see if the shells go all the way foward and drop out the front end of the magazine tube, as they should and this will ensure that there is no blockage of the magazine tube. If shells bind or get stuck inside the magazine tube, then there must either be an obstruction, dent or bend to the magazine tube. Now what makes the shells come out of the magazine tube is the magazine spring pushing on the follower, which in turn pushes the shells out of the magazine tube. So make sure that shells freely move through an empty magazine tube is a simple check to see if there are problems with the magazine tube as I already mentioned. You already mentioned that you added a heavier spring, I am a huge fan of Wolff magazine tube springs for more powerful feeding. The follower could be getting stuck or dragging. This can be attributed to something with the follower like being deformed. But can also be an issue with heavy debris fouling inside the magazine tube, so you may try using one of the Brownells magazine tube brushes to swab it out. By cleaning out the magazine tube, you can eliminate that it isn't crud or fouling causing the issue. As already mentioned, make sure that your magazine tube extension isn't binging up the spring either. Next is to look at what holds and releases the shells from the magazine tube, which is the shell latches. As if you are behind the gun shooting it, there is a right and left shell latch. The left shell latch is the one that is responsible for releasing a single shell from the magazine tube as the pump action is cycled rearward. The right shell latch is what catches the second shell and holds it so it doesn't release from the magazine tube when the action is cycled rearward. So if the issue is that the left shell latch isn't moving out of the way consistently to allow a single shell to release from the magazine tube, that you need to look at the shell latch tip to make sure it is in tact. Also look at the action bar assembly, (which is the forend assembly that consists of the forend, action bars, and a spanner nut at the front that keeps things connected together. If the left shell latch isn't moving out of the way, then the left action bar may be bent and not pushing the left shell latch out of the way. The forend (front stock) could also be out of proper alignment, which is twisting the action bars and not allowing the left shell latch to move out of the way to release a shell from the magazine tube. A bent action bar will cause this issue as well (don't bend the action bars, as they are responsible for 7 out of the 8 cycles of operation. Another possible cause is that there is something going on in the left action bar channel of the receiver, that is causing left shell latch to not push out of the way, very common when someone stakes the left shell latch and accidentally pushes metal into the action bar track. If the gun had a side saddle type shell carrier added at anytime, the issue may be that whoever installed it may have over tightened the mounting screws and bent the receiver. A broken ejector tip can also be the culprit, as the front tip supports the barrel to keep it from turning inside the receiver. If broken off, the barrel can slightly twist out of alignment when cycling, and this can result a gun that sometimes feeds/locks/unlocks, and every once in a while may bind or not work correctly. So check the frong tip of your ejector and see if its damaged in any way. As for figuring out what may be the other possible issue, please try and give us a better description and we may be able to help diagnose the cause and come up with a solution. Examples would be: The shells are getting stuck coming out of the magazine tube The shells are not being lifted up by the carrier to go into the chamber Shell are getting stuck going part way into the chamber Shells are not extracting and coming out of the chamber as the action is being cycled rearward Shells are extracted out of the chamber, but they are not going out the ejection port (not ejecting) The gun will not unlock the action and go rearward after firing a live shell, but will with a dummy round CY6 Greg Sullivan "Sully" WeaponsArmorer SLR15 Rifles Defensive Edge Training (763) 712-0123 Shells are occasionally binding up when loaded into the magazine tube, always the 4th/5th or 6th shell. The initial few shells load smoothly, then will abruptly stop (the last shell loaded simply won't move and must be chambered to be removed). After trying to diagnose and swapping the magazine spring, trigger mechanism and cleaning the magazine tube, I was still having the issue. Following the advice from this thread, I loosened the screw that secures the sling swivel clamp between the barrel and magazine tube. After testing with a few cycles of dummy rounds, that may have been the issue (over tightening that screw pulling the barrel and magazine tube towards each other, creating a small seem that the shells/spring/follower were catching on). I appreciate all the time and assistance on this, if the problem persists I'll be coming back to see if we can get it sorted. |
Good, bad....I'm the guy with the gun. - Ash Williams
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Originally Posted By backbencher: Have you tried it w/o the extension installed? Happening at the “4th or 5th shell” makes me think this may be at least part of the problem as well. OP, did you recently remove the extension, perhaps while cleaning the gun? If so, are you CERTAIN you removed and reinstalled the extension correctly? There is a specific way to do it. If done incorrectly, it can deform where the mage tube and extension meet. Beyond that, I would look at the shell latches as likely suspects. If they are bent or displaced, they can create the kind of malfunction you are describing. |
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