870 Misfeeding Problem

[mmattockx]

I have an older wingmaster that is going to be my bear/plinking/home defence gun and it has an intermittent feed problem. It has an 18.5" barrel and a +2 mag extension from S&J. I have only shot a few rounds through it to test the function, as I am cutting the stock down and planning on refinishing the wood furniture before using it regularly.

When I load more than 4 or 5 rounds in the mag it will feed two rounds at once and jam until I pull the extra round out of the receiver. If I only load 2 or 3 rounds it works fine. What is likely happening and how do I fix it?

Thanks,
Mark

 

[badboybeeson]

Spring could be to long, cut of an inch .
bbb

 

[Fusilier]

This sounds like a problem of the gun's 'timing'. Inside the 870 are two spring loaded "Shell Latches", one on the left and one on the right. One keeps the next shell from being released too soon (i.e. until the pump is almost all the way to the rear). The other keeps the rest of the shells in the magazine from coming out until the first one is out of the way (i.e until the pump is on its way back forward after the shell is loaded into the chamber).

It is possible that the spring action on the second one (I can't remember if it is the left or the right one) is a touch weak. Weak enough that when you have the magazine fully loaded and the mag spring is under full compression, it overcomes the second shell latch releasing the next shell in the mag tube prematurely. However, when the mag isn't full, the spring isn't pushing on the shells as hard and the Shell Latch can hold its own.

Check out my explanation over at this thread:

http://www.canadiangunnutz.com/forum/showthread.php?t=409710&highlight=870+timing

All I did was use a little finger effort to bend the Shell Latches inwards a bit to increase their 'action'. Worked on my 870 and I've never had a double feed since.

I have an older wingmaster that is going to be my bear/plinking/home defence gun and it has an intermittent feed problem. It has an 18.5" barrel and a +2 mag extension from S&J. I have only shot a few rounds through it to test the function, as I am cutting the stock down and planning on refinishing the wood furniture before using it regularly.

When I load more than 4 or 5 rounds in the mag it will feed two rounds at once and jam until I pull the extra round out of the receiver. If I only load 2 or 3 rounds it works fine. What is likely happening and how do I fix it?

Thanks,
Mark

 

[mmattockx]

Spring could be to long, cut of an inch .
bbb

How stiff should it be when loading the 7th round into the mag? It is very stiff and takes a very hard push to get that last one into the mag.

This sounds like a problem of the gun's 'timing'. Inside the 870 are two spring loaded "Shell Latches", one on the left and one on the right.

<snip>

All I did was use a little finger effort to bend the Shell Latches inwards a bit to increase their 'action'. Worked on my 870 and I've never had a double feed since.

Makes perfect sense to me, I will go have a close look at the latches and see if they need a bit of tweaking.

Thanks,
Mark

 

[easy]

I must agree with 'fusilier' on this one. It's a shell latch problem and it will be the left shell latch that is responsible for timing the subsequent shell.

However it may not be just a simple bend. The part of the latch in question may be worn to the point it needs to be replaced.

I'm not adamant about cutting springs.

 

[badboybeeson]

should not be that stiff, the springs i ship the tube with may be a little longer then needed ,some batches may have spring for a +3
bbb

 

[mmattockx]

should not be that stiff, the springs i ship the tube with may be a little longer then needed ,some batches may have spring for a +3
bbb

No worries, I will trim 1" off the end and see if that helps. If nothing else, it will be easier on my thumbs. Even with a shortened spring, I am sure there will be plenty of tension to ensure proper feeding.

I did some more testing last night with plastic practice rounds and it would misfeed at random regardless of the number of rounds in the mag. Sometimes it would feed all 7 fine, other times the last two rounds would feed together. It definitely seems to be a latch issue and not the spring tension as I thought at first.

Mark

 

[easy]

Keep in mind that sometimes plastic practice shells, or even brass rimmed ones wear out from repetitive use at the rim and slip off the latches and cause issues in testing. If it's doing it with fresh live rounds then it's a different story for sure.

 

[mmattockx]

Keep in mind that sometimes plastic practice shells, or even brass rimmed ones wear out from repetitive use at the rim and slip off the latches and cause issues in testing. If it's doing it with fresh live rounds then it's a different story for sure.

I did some more testing tonight with live ammo and couldn't recreate the problem, no matter how fast I racked the slide or how many I loaded in the mag. It would appear that my practice rounds are the culprit, as suggested. I will finish my work on it and then get out for more field testing to confirm that it is indeed OK, but it is looking better already.

Thanks for the help,
Mark