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Discussion in 'Rifle Discussion' started by james83, Jun 18, 2012.
Is a shell stop on one side binding ? If one got tweaked, or debris behind it, when you removed and replaced the forend assembly, it could cause what you are describing.
+1 I'd pull off the magazine cap, remove the spring & follower and make sure the mag is free of crud and doesn't have any dimples besides the factory ones near the end (if it has those). Also make sure that foreend isn't contacting the receiver when you pull it back (making it short stroke).
PM you so if you need help let me know.
Tony Portland, Oregon Area
Weak mag spring. Get a new one. Clean the inside of the mag tube and the follower. Test: take the mag spring out and stretch it out about four or five inches longer. Put back in and shoot. If this corrects the problem, get a new spring. Very common problem.
I had the same problem with a weak magazine spring. Hope that helps.
I'd shy away from a conclusion of a weak magazine spring for two reasons: the gun works fine with the factory forearm, and the gun (an 870 express magnum) is probably relatively new. This is a classic case of home gunsmithing where one's early attention to Sesame Street can be quite valuable. "One of these things is not like the other."
There is something about the replacement parts that is mechanically different from the factory part. Slow and careful (safe) operation of the action under very good light, examining all bearing surfaces and interactions of parts should point to the anomaly. My guess is that the new forearm is preventing a full travel of the slide. (credit to DoubleTapDrew).
The moving parts that let all but the last round eject, are the same exact parts that let the last round eject. The only diff is the pressure on the last round being less because the spring is compressed very little with just one round in it. Streach the spring out and run some ammo through it. You do not need to fire the rounds off. Just eject all of them by hand. It will not hurt the spring in any way.
keep shoving shells into it so that it is never on the last one in the magazine
Leave it to sheepdip for full employment of the KISS principle.
I chose my words "I would shy away from...weak magazine spring..." because I would not completely ignore that solution (and OJ has the diagnosis portrayed well, and in fact that was my first reaction too). A newer, stronger magazine spring may well cure the problem.
BUT: The gun should operate identically with either forearm attached (if for no other reason than the owner may wish to switch back on some future date), and a new spring not curing the problem would be money wasted. (I still am of the belief that since the gun is not old, the spring is not weak.) Stretching the spring is a diagnosis tool and/or a quick fix (in case of a weak spring) but should not ever be a long-term solution. Coil springs are manufactured each to their own diameter of material and wrap, and changing that original wrap defeats the engineered purpose for that specific diameter of steel, coupled with that specific wrap to produce a specific tension. A weak spring stretched to produce more tension will before too long revert back to its original weakness and unreliability. Toward example, a malfunctioning "thumb-click" ball-point pen can very often be fixed by dismantling the pen and stretching the spring. Before too long, it will begin the identical malfunction.
James, I would avoid altering that new Hogue forearm unless the problem is quite obvious, and easily remedied (as you speculated) by removal of a very small amount of material. My procedure would be to send it to Hogue specifically describing the problem and the gun it is fitted to (perhaps accompanied by copies of purchase receipts). Gun companies are the holdouts in manufacturing America, in that they still for the most part treat their customers right. You may be doing that company and its customers a favor by reporting your discovery.
thanks for the kind words spitpatch.
No sweat. While OJ and I are dinking around with stretching springs, carving off pieces of forearm and mailing stuff to manufacturers, you're loading the friggin' gun. It deserved recognition.
One more look.
The gun has no idea how many shells are in the mag tube. The inner workings of the gun function the same each time you cycle the action. If the Hogue will function on the first round it will function on the last round. Unless your gun has some type of demonic possession. So, the only thing that changes in the inner workings of a pump shot gun, is the spring tension of the mag tube.....Everything else is 100% the same 100% of the time. I see from your last post that you say the round got stuck in the chamber. It was my belief that we were taking about the round getting stuck in the mag tube. Cheap ammo will stick in the chamber after fireing sometimes. Keep the chamber clean and a good chamber polishing will do wonders. I think that you have some kind of issue that is not allowing the mag tube release to fully release the round into the open chamber and the extra spring pressure from the loaded mag tube is pushing hard enough to over come this on all but the last round(least amount of spring pressure in a loaded mag tube) I am still 100% sure that if you stretch you mag spring out to increase the spring force it will work. But, it will not cure the problem. I would have it fixed in about one minute, if I could get a look at it.
Well, my vote is against demonic posession. With the operator having used another brand new spring, I'm also leaning futher away from my first impression of inadequate spring strength.
I also would like to know a source of "cheap ammo" for a 3.5" 12 ga.
And, like OJ, I am confused now about "stuck in chamber" vs. "stuck in mag tube".
Kudos to James for a pretty darned good elimination of variables using a friend's gun for parts (good friend too!). Make sure you tell Hogue about your gun being the monster super magnum one.
This is fun.
Not sure he ever said what size/type/length of 12 ga ammo he was using. And the mag spring from his friend's gun was not from a super mag, just from a standard 870. so, my question is, that if the gun can use the longer 3.5 inch rounds, does it indeed require a stronger mag spring.
Weak mag spring, get a wolff as I do for all my shotties.. I change them every few years too. Polish the mag follower with 2000 grit as well. "From your buddies gun" does not cut it, what is your life worth?
In James's defense, he only used the buddy's spring to diagnose. (Pretty good idea, by the way). I'm not a shotgun guy primarily (only use them for hunting and occasional trap and skeet), and have never found any need to replace a magazine spring on any of them (the Model 12 is probably approaching 85 years old right now.).
But: if OJ's diagnosis technique (stretching the spring) proves a "work around" to the problem, I would repeat my warning to not allow this to be the solution to the problem. The suggestion of an aftermarket spring (such as a Wolff) might then be in order, since a stock one ( can we assume the springs were identical from both James's gun and the buddy's?) did not solve the problem.
None of this would tell any of us why the gun works fine and as it should with a factory forearm and not with the Hogue.
Most gunsmithing problems are like solving a puzzle.
1) Factory fore end works
2) Hogue fore end leaves last shell half out of mag tube.
3) Stretching spring fixed problem until spring compressed to standard size.
4) Hogue worked on buddies gun, but is was not the same model.
So, there is a latch that is pushed in by the slide rods on the slide that unlocks the shell catch on the mag tube. This lets the fresh shell inter the loading ramp, to then be sent to the chamber as you close the bolt, by pushing the fore end forward. If you look at the shell as it is stuck in the half way position you will see that it is being held by that end of the shell latch. The pressure of the extra loaded rounds was enough to over come the latch not being open all the way. The extra pressure of the stretched spring was enough to over come the latch. The Hogue fore end is not opening the latch 100%. It is not going all the way back. To test, you need to remove the trigger group. Then as you pull the fore end back you can see how the latch works. See if it goes all the way in, or if is only moves a little. You should be able to cycle shells with the trigger group out. Remove the offending material and you have performed your first exorcism.
I fully load my shotties when in service and have had factory springs get so weak (Mossberg 500) that the last round would not feed. That was a wake up call to go for Wolff springs and change them like diapers. I save the old (Wolff) springs because they are probably still good and a buddy may need one sometime
I like it when things come full circle.