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Discussion Starter #1
Going through old boxes today and found a disassembled 870 from 15-20yrs ago....The reason I took apart was a broken SINGLE ARM pump-any ideas where to find a SINGLE ARM part.
 

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Zant, are you sure it's an 870, and a not a Model 31? I've never heard of a single action bar 870, two is what made the 870. Can you post a pic of it? If it's broke where I think it is, it's repairable, and a whole lot cheaper to do than finding, and paying the price of a replacement.
 

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Discussion Starter #4
Zant, are you sure it's an 870, and a not a Model 31? I've never heard of a single action bar 870, two is what made the 870. Can you post a pic of it? If it's broke where I think it is, it's repairable, and a whole lot cheaper to do than finding, and paying the price of a replacement.
No-it's a freaking Mossberg500a....I was sitting here looking at my buddys 870 and just typed it-elderly brain fart...
 

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Discussion Starter #6
I found the pump with single arm but in .410 and 20ga only at Numrich,will continue looking,thx.
 

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I found this, and seen posts from guys in the same predicament as you do it:
"any two arm slide will work, just remove the one bar. It's the same basic part. It's a copper or bronze pin on most models, steel on some. Takes like five mins to pop the one arm off the modern slide tube. First caveat here is the standoff bushings. Those spiral springs on the original mag tube that keep the slide tube from rubbing the tube all over. Your original slide tube is a straight wall tube. A modern slide tube will have the dimples on the tube and those won't work with the spirals. Ideally, you'll want to find on old straight wall two arm on Ebay....still a common part. Second best, a modern dimpled slide. You'll need to either pop those spirals off the old tube and hope they didn't rust it through too bad that it can't be cleaned up....or you'll just need to buy a new mag tube. If you go new mag tube and new dimpled slide tube, you're looking at $50. Old two arm straight wall slide tube, you're looking at $25. That gun can be made whole again for not a lot of dinero, though. Well worth the effort."

A pinned action bar forearm will be a bit looser than the original welded part. It's not a detraction, though. Tack weld it if you don't like it that way. If you're all set to weld, just grab the bar from a current tube and weld it to your old tube.

Yours is a 7 3/4" (7 5/8"). Measure it from the edge of the action bar collar to the front edge of the threads. If you go for the new slide tube, measure it the same way.

Measuring your forearm to find the tube size....another post of mine;

"On the inside of your forearm, on the back side, you'll see two tiny ledges machined. Pretty close to 3/4" between the two. The action bar attach collar on the action slide tube fits there when the wood is mounted. Measure from the backmost ledge, it'll be where the slide tube back edge is, all the way to the front of the wood on your forearm. At that front, you'll find another tiny ledge just short of the front edge of the forearm itself. That'll be pretty near to where the front of your slide tube will hit, barring individual manufacturing diffs of course. So backmost ledge to frontmost ledge and you'll get your tube size."
 

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Discussion Starter #8
So basically I can buy a dual arm pump and remove 1 arm and use that....or could I buy a dual arm-remove the 1 side and use that setup??
 

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Messing with you Brother. (Sorry) Numrich, E-Gun Parts, Brownells, Midway, probably all the sites you've already visited. Good Luck Brother.
 

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From an old Numrich catalog:

Item # 54640 12 gauge action bar, 7 5/8" length, bar type single, Price $37.05

Catalog # 25, page 513. Mossberg manufacturer number #11603. If Numrich doesn't have it, at least here is the Mossberg number. Makes it easier to get a part that will fit from someone else.

Wolverine Supplies lists one for about $81.00. Just type in "Mossberg Part Number 11603" in your Search Engine and it should take you there. Good luck!
 

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Discussion Starter #14
If the catalog is older than 1 yr-that's all gone.....Jacks-rifle only....still searching---#11603 is DUAL arm...THX
 

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If the catalog is older than 1 yr-that's all gone.....Jacks-rifle only....still searching---#11603 is DUAL arm...THX
Did you look at the website? I glanced at it and read 'single arm'. If not - maybe that part could still be used if the other arm were removed? I don't know - just asking...
 

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Wolverine Supplies lists one for about $81.00. Just type in "Mossberg Part Number 11603" in your Search Engine and it should take you there. Good luck!
Wolverine states that they are a Canadian company and won't ship outside of Canada.
 
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Wolverine states that they are a Canadian company and won't ship outside of Canada.
Yes, I understand that. The good thing about TFF is that there are a lot of good Canadian folks who are TFF members. I do believe that there is a way for an item like this could be purchased legally by one of our members and shipped to another. We are not talking guns or ammunition - just a hunk of metal.

Canada has some stupid laws for businesses to obey just like we do. What would be illegal under Canadian law for a corporation because of international treaties surely wouldn't apply to transactions between citizens. Again, we are not talking ammunition or guns here - just a piece of machined steel. Not a gun. Certainly not military hardware.
 

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Discussion Starter #18
Did you look at the website? I glanced at it and read 'single arm'. If not - maybe that part could still be used if the other arm were removed? I don't know - just asking...
Those were for .410-different diameter....bummer
 

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So basically I can buy a dual arm pump and remove 1 arm and use that....or could I buy a dual arm-remove the 1 side and use that setup??
You got it, but....the catch is the newer two arm versions, come in two lengths, and you want the longer one.
I'll take an educated guess, yours has the end broke off where it connects to the bolt? That's the weak point and common problem common problem, and why there isn't any of them found for sale. If you still have the piece that broke off, Option B is having it Tig welded back together.
FYI trivia...Mossberg couldn't go to the two arm style, until Remington's 870 patent expired.
 

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Discussion Starter #20
You got it, but....the catch is the newer two arm versions, come in two lengths, and you want the longer one.
I'll take an educated guess, yours has the end broke off where it connects to the bolt? That's the weak point and common problem common problem, and why there isn't any of them found for sale. If you still have the piece that broke off, Option B is having it Tig welded back together.
FYI trivia...Mossberg couldn't go to the two arm style, until Remington's 870 patent expired.
Thx-that's probably what I'll do-found dual arm and ordered....yep-7.75"--they have 4 different lengths.
 
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