Matt in TN Posted October 9, 2014 Share Posted October 9, 2014 <iframe width="560" height="315" src="//www.youtube.com/embed/Ae6kvStq7d8" frameborder="0" allowfullscreen></iframe> I've been having a new problem with what I thought was "short stroking" my 870 while trying to shoot faster. I had my daughter video me tonight to make sure, and I just don't see how I could stroke the pump any farther or harder. Shell #1 loads and shoots fine. Shells 2 and 3 are the failures I'm describing - I thought it was short stroking, but maybe it's some other kind of failure to feed. Shots 4, 5, and 6 were normal, with the exception of shot 5 throwing a fireball out the ejection port. I assume this is the cheap ammo I'm using (for the first and last time tonight) as it happened several times and I've never seen it before. After shot 7 I really did short-stroke to the point where it didn't eject, and I caught it and fixed it on the fly. Shot 8 cycled normally. The video is normal speed through the loading (I'm new to load 2 and figured I could use the practice), and switches to slow motion as soon as the shooting starts. I'm mainly concerned about figuring out what's causing the failures to feed, but if anyone can offer tips on my loading I'd appreciate all the help I can get! Link to comment Share on other sites More sharing options...
Matt in TN Posted October 9, 2014 Author Share Posted October 9, 2014 Edited for double post. Link to comment Share on other sites More sharing options...
Matt in TN Posted October 9, 2014 Author Share Posted October 9, 2014 And now a double-post that I can't figure out how to delete. Help!!! Link to comment Share on other sites More sharing options...
GrumpyOne Posted October 9, 2014 Share Posted October 9, 2014 I merged your 2 posts on it... Link to comment Share on other sites More sharing options...
NisilS14 Posted October 9, 2014 Share Posted October 9, 2014 I would check the magazine spring, then the carrier spring and possibly the feed latches. Notice you have a longer tube on it check to make sure it has adequate spring tension. If that seems in order see if the carrier spring is not working properly, it's known to weaken over time and not lift the shell all the way into the chamber. If that does end up needing to be replaced a 1100/870p carrier spring is an upgrade from the standard one. If the feed latches are sticking, check the action bars, the feed latch is pressed over by the action bars to allow shells to feed from the tube by the beveled part of the action bars and it may not be catching to push it over. The problem is with either the feed latches or action bars. Link to comment Share on other sites More sharing options...
Matt in TN Posted October 9, 2014 Author Share Posted October 9, 2014 Thank you sir - this happens with two different feed tubes, springs, and followers. The tube on there currently is a Nordic +5 and there is 12" of spring left hanging out of the tube before compression (as they recommend). The feed latches and carrier spring appear to be fine when cycling dummies or even running the gun just a little bit more slowly (maybe 0.75 second splits). Any idea how to really check these? Is there a specification I can measure? It only happens randomly when I am shooting faster than about 0.5 second splits. When shooting slower it functions 100%. Link to comment Share on other sites More sharing options...
Matt in TN Posted October 9, 2014 Author Share Posted October 9, 2014 I merged your 2 posts on it... Thanks! Any idea how to embed the video? Link to comment Share on other sites More sharing options...
GunCat Posted October 9, 2014 Share Posted October 9, 2014 (edited) Does it only (randomly) happen with the first or second shell out of fully loaded mag tube? If that is the case I suspect the stack of shells in the magazine tube are moving forward* when the gun recoils and the action is already starting to close before the shell can move back and fully exit the magazine tube. * (Actually the shells are remaining in place but the gun moves backwards. Inertia in action - More shells in the tube equal more weight to work with inertia) A bit more spring pressure may fix that issue (leave the Nordic spring about 16” longer than the tube on your gun next time to start with). You can simulate that fix by putting 2 shells between the end of the spring and the end of the mag tube (temporarily reducing capacity, but increasing the spring pressure) Edited October 9, 2014 by GunCat Link to comment Share on other sites More sharing options...
Matt in TN Posted October 9, 2014 Author Share Posted October 9, 2014 Interesting idea - thanks. In my head it happens randomly throughout the tube, but I confess it usually happens at matches and I can't confirm that. I'll try the added spring pressure idea and see. The spring is fairly stout at 12" - I started at 16" and could barely get the cap on. Maybe that's exactly what it needs though. Link to comment Share on other sites More sharing options...
Matt in TN Posted October 12, 2014 Author Share Posted October 12, 2014 I would check the magazine spring, A bit more spring pressure may fix that issue (leave the Nordic spring about 16” longer than the tube on your gun next time to start with). This appears to be the case. I installed the 6rd tube and the 7rd spring I have on hand and it cycled fine (for 6 rounds anyway). I'll order a new spring from Nordic and try it again with the 9rd tube. Funny - everything I've read says pump spring pressures can be almost nothing as compared to semi-auto spring pressures and work fine. Guess that's not the case after all - Link to comment Share on other sites More sharing options...
RJH Posted October 13, 2014 Share Posted October 13, 2014 I find it hard to believe it is spring pressure on your pump. I also run a pump with virtually no spring pressure and the gun cycles fine with splits in the upper 30s which is as fast as I can shoot a pump. I would look for a burr or sharp edge where your mag tube and extension come together. Especially if it runs fine with a short ext. and or factory length tube. Link to comment Share on other sites More sharing options...
RJH Posted October 13, 2014 Share Posted October 13, 2014 Also it looks in the video like you have a barrel clamp on the gun, if they are to tight they can do the same thing. Link to comment Share on other sites More sharing options...
bigbrowndog Posted October 13, 2014 Share Posted October 13, 2014 870's are notorious for the staked in feed latches to work loose, I watched the late great Eddie Rhodes have to deal with this issue during a DPMS Trigun match. If the 870 is a former LE gun they get cycled a lot and not taken proper care of so stuff wears out quick. if the gun has had a lot of rounds thru it without adequate lubrication they will wear out parts faster. If the feed latches have somehow worked loose they can be tight one secoond and loose the next so its difficult to diagnose, especially with the gun put together. It is much easier to check these with the gun completely apart and nothing in the receiver except the the latches. If they are loose its an easy fix to get them restaked in place, most good old fashioned gunsmiths can do this, or send it to Carlsons, Briley, or Simmons. From what I can see from your video that is the first thing I would look at, you can eliminate the extended spring, ext tube and such by simply trying to duplicate the malf. with the stock 5 shot tube. trapr Link to comment Share on other sites More sharing options...
AKJD Posted October 13, 2014 Share Posted October 13, 2014 (edited) The gun should work fine if the feed latch stakes come loose because the latches are held in place by the front trigger plate pin and the trigger plate assembly. Remington started staking them because people would take the gun apart then had trouble putting them back in correctly. Check to make sure there isn't a problem between where the mag tube and the extension mate that is interfering with the spring, follower or rounds. Check for burrs on the ends of the latches, also that that there isn't anything obstructing the ends of the latches from moving when the timing cuts on the action bars engage. Edited October 13, 2014 by AKJD Link to comment Share on other sites More sharing options...
Matt in TN Posted October 19, 2014 Author Share Posted October 19, 2014 (edited) OK - I detail stripped the trigger group, receiver, and action bars, and everything looks good. New Nordic spring came in, and I trimmed it to leave 18" of free length, and could barely get the cap back on. This spring is STRONG! Nordic +5 extension with 18" free spring length, loosened one full turn and clamped to the barrel (recommended way to minimize barrel stress from the clamp) gave me FTF on round 3, 5, and 7: http://youtu.be/piyJs6APgzY Same extension and spring with no clamp, and tightened fully (thinking the gap between the extension and the factory tube and/or misalignment of the extension might be causing my problem. Gave me FTF on rounds 2, 3, 4, 5, and 6: http://youtu.be/DDKZB30o-h8 So I revisited the 6rd tube with the 7rd spring to see if it was a fluke last time. Flawless action with 0.41 second splits: http://youtu.be/LZ58pcXiLKw Same spring with a 7rd tube gave me FTF on rounds 3 and 4: http://youtu.be/R2JWdJLWaAs It HAS to be tube and/or spring related. The spring on the +5 extension is hugely stronger than even the 7rd spring in the 6rd tube. There are no burrs on the end of my factory tube, and rounds slide freely inside the tube even without a magazine spring. I stacked 6 rounds in a line outside the tube just to be sure, and the 6th round sits well past the factory tube/extension transition. You would think that if the transition were at fault the first round out of the 6rd tube would FTF - or the last five rounds out of ANY of the tubes would feed fine. WTF?!?!?!?!? Edited October 19, 2014 by Matt in TN Link to comment Share on other sites More sharing options...
AKJD Posted October 19, 2014 Share Posted October 19, 2014 (edited) A couple thoughts. Does the gun feed OK if you just cycle a full magazine through without firing using the action bar release. Use a pair of calipers to check the inside diameter of the shogun mag tube and the extension to make sure they are not flared in from over tightening. Is the end of the aftermarket magazine spring squared up so there is not a pointed end going into the follower. If not use a pair of pliers to bend the end in towards the spring so it sits more square in the follower. This can cause hang ups I know from experience. Factory springs have the full loop at the end to prevent this. Will the follower slide up and down freely through the magazine and extension without a spring in it. Is the follower the original plastic or aftermarket. Edited October 19, 2014 by AKJD Link to comment Share on other sites More sharing options...
Matt in TN Posted October 20, 2014 Author Share Posted October 20, 2014 A couple thoughts. Does the gun feed OK if you just cycle a full magazine through without firing using the action bar release. Use a pair of calipers to check the inside diameter of the shogun mag tube and the extension to make sure they are not flared in from over tightening. Is the end of the aftermarket magazine spring squared up so there is not a pointed end going into the follower. If not use a pair of pliers to bend the end in towards the spring so it sits more square in the follower. This can cause hang ups I know from experience. Factory springs have the full loop at the end to prevent this. Will the follower slide up and down freely through the magazine and extension without a spring in it. Is the follower the original plastic or aftermarket. Thanks for the help - the gun cycles find while using the action bar release, or while "firing" dummy rounds. I did bend the follower end of the spring inward as they recommend, but maybe I need to revisit this bend to see if I can even it up some more. I'll check the flare - it's not visible, but I need to measure it. The follower in all the videos and tube variations is a Wilson Combat plastic like this (below). It does slide freely up and down the tube with no spring. I started with the Nordic follower, but found it bound sometimes in the tube so switched to this (I have several types of followers on hand) and there was no more binding. Maybe I should revisit the Nordic follower and see if I can figure out what, where, and how exactly it was binding? Link to comment Share on other sites More sharing options...
Matt in TN Posted January 25, 2015 Author Share Posted January 25, 2015 I gave up on this for awhile, but I just can't let it go. I did find a VERY slight restriction in the middle of my factory mag tube, so I turned down a piece of black pipe to 0.920" OD so it would just barely fit in the end of the mag tube. I then turned down an extra 0.010" for 3" on the end and cut a slit so it would hold sandpaper. A lot of time and oil later, with 320 and 600 grit paper, and the mag tube is uniform and very smooth. That didn't fix it either. I did find that after shooting, and when I experienced the FTF, the next shell that SHOULD have cycled was held by the right (secondary) shell latch - not the left (primary) shell latch like it should have been. I played with the shell latch geometry awhile and did find a worn screw holding my side saddle on that MIGHT have let the right shell latch move backward a little and made it easier for it to catch the rim of the shell. Removing the side saddle and reinstalling the factory trigger pins (with no wear at all) changed nothing. The shell latches function completely normally and have no debris or extra wear. So I fabricated a bracket to mount my iPhone underneath the shotgun and take a 120 fps video of the failure happening. Below is the tube just before firing: And below is the tube just after firing: The only thing it can be is the inertia of the 9 shells in the tube being pushed forward (or more accurately, staying in place while the shotgun moves rearward). I have a +5 extension and 18" of free spring length outside the tube. The magazine spring is VERY strong, and yet it happens unpredictably whether there's 9 rounds in the tube or 3. The physics make sense - but what I can't figure out is why I seem to be the only guy having this problem?!?!?!?! Why does everyone else's shotgun work fine, even with less magazine spring force? Link to comment Share on other sites More sharing options...
kurtm Posted January 25, 2015 Share Posted January 25, 2015 I can assure you that "not everyones" 870 works but yours! I have put on many a shotgun class, both for competition and for L.E. and by far the most problematic shotgun is the much touted 870. It is a rare 870 that just runs and runs. Most have problems and we used to waste tons of class time diagnosing and band aiding 870s. Now we just bring extra guns. I've got no insight for you for your problem, but don't feel like the lone ranger. Link to comment Share on other sites More sharing options...
Matt in TN Posted January 25, 2015 Author Share Posted January 25, 2015 Actually, that DOES help, Kurt - thanks! How do the SuperNovas do? They seem to be the favorite lately for pump gunners. Or is there something else I should be looking at? Link to comment Share on other sites More sharing options...
colbyjack Posted January 26, 2015 Share Posted January 26, 2015 Email remington and see what help or advise they can give to troubleshoot. I thought 870 was the AK47 of shotguns. Link to comment Share on other sites More sharing options...
WCK Posted January 26, 2015 Share Posted January 26, 2015 One other thing to look at is the Nordic magazine tube extension nut. If the inside of the Nordic magazine tube extension nut is not concentric the shells maybe hanging up when they transfer into your 870 magazine tube. This is easy to check, assemble your 870 with only the Nordic magazine tube extension nut (no spring or follower), look inside and see if you can see the edge of your 870 magazine tube. Use a flash light. You might also try to put a small chamfer on the inside edge of the end of your 870 magazine tube. Link to comment Share on other sites More sharing options...
StealthyBlagga Posted January 26, 2015 Share Posted January 26, 2015 (edited) I just saw this thread. Indeed, it does sound like your shells are "moving forwards" in the magazine tube under recoil due to their inertia. This phenomenon is actually quite well known to Remington - it is called "shell surge", and is the result of taking a gun designed for duck hunting and adding a magazine extension to make it "tactical". A stronger magazine spring is only a BandAid. And the folks who claim not to have a problem are often MUCH slower at pumping the gun. When I ran an 870 I had the same problem, and could only fix it by doing what Remington should have done decades ago - I re-timed the action bars by welding on extra metal then recutting the cam surface that actuates the shell latch. The result was a bit ugly, but it completely solved the problem. In the end I got rid of the gun, but still have the modified pump handle. If you want it, send me your address and I will drop it in the mail for you... I have no use for it any longer. Edited January 26, 2015 by StealthyBlagga Link to comment Share on other sites More sharing options...
Matt in TN Posted January 26, 2015 Author Share Posted January 26, 2015 I just saw this thread. Indeed, it does sound like your shells are "moving forwards" in the magazine tube under recoil due to their inertia. This phenomenon is actually quite well known to Remington - it is called "shell surge", and is the result of taking a gun designed for duck hunting and adding a magazine extension to make it "tactical". A stronger magazine spring is only a BandAid. And the folks who claim not to have a problem are often MUCH slower at pumping the gun. When I ran an 870 I had the same problem, and could only fix it by doing what Remington should have done decades ago - I re-timed the action bars by welding on extra metal then recutting the cam surface that actuates the shell latch. The result was a bit ugly, but it completely solved the problem. In the end I got rid of the gun, but still have the modified pump handle. If you want it, send me your address and I will drop it in the mail for you... I have no use for it any longer. Great info - I had wondered about modifying the timing and/or length of the latches too. PM sent! Link to comment Share on other sites More sharing options...
colbyjack Posted January 26, 2015 Share Posted January 26, 2015 Post pictures when you get it. That's a awesome fellow member. Very nice of ya stealth... Link to comment Share on other sites More sharing options...
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