Here is a link to a schematic diagram which gives all the part names CLICK

I got into this to help a friend with his family history shotgun. It was in rough shape. I had never had one of these apart but this one definitely needed complete disassembly, thorough cleaning and some parts. I searched in vain for disassembly instructions. Then I was pointed to a single post on another site that gave a few hints that got me going. Biggest concern was dealing with some fairly heavy duty action springs. Here is my experience. If you ever do get into a complete tear-down of one of these guns the first piece of advice is WEAR EYE PROTECTION. Once you have your eyes protected, here is what you will need to do.

1. Remove forend
2. Turn top lever to unhook barrel
3. Remove barrel
4. Remove butt stock
a. remove butt plate or recoil pad
b. remove butt stock bolt 7/16" hex head
c. separate butt stock from frame
5. Remove trigger guard

Here is what you see now

6. Remove the hammer spring assembly (bushing, spring, plunger). EYE PROTECTION This is easier than it looks. Pull the hammer completely back. The small hole in the bushing will align with a hole through the plunger. Insert a small pin punch or a small finishing nail completely through. Now slowly release pressure on the hammer. The hammer spring assembly will be compressed and free. It may just fall out under gravity or you can gently wiggle it free. If you need to tear down this assembly, place it lengthwise in a vise and gently squeeze until you can remove the pin punch then slowly reduce the vise pressure until the spring is unloaded. The three parts (bushing, plunger and spring) can now be separated, cleaned, lubed and reassembled, again in the vise.




7. Remove the top lever plunger and spring. This can be done by grasping the flat plunger with needle nose pliers and forcing a little more spring compression to clear the locking bolt connecting rod and then pulling out sideways. Good to keep the frame wrapped with a cloth in case you lose grip and the spring flies. EYE PROTECTION


8. Remove the locking bolt plunger and locking bolt plunger spring. The pointed plunger is held by spring tension into a small dimple in the locking bolt connecting rod. Keep the spring covered with a cloth or your hand while gently forcing the tip of the plunger out of the dimple (surprisingly difficult for the short distance involved). A small flat screwdriver can be used to leverage it out. This can fly if you are not careful. EYE PROTECTION

Front



Back



9. Remove the hammer. Punch out the hammer pin. Note that one end is fluted. Punch this pin out from the other side, as the fluted portion will not pass through the hammer


10. Remove the top lever. Rotate and pull. Comes out easily.

11. Remove the locking bolt/locking bolt connecting rod assembly. Punch out the locking bolt pin. Note that one end is fluted. Punch this pin out from the other side, as the fluted portion will not pass through the locking bolt. The pin holding these two parts together is peened over and not meant to be removed.

12. Remove the firing pin. Remove the firing pin retaining screw. The firing pin will drop free. There is no spring involved. The screw simply stops the pin from falling into the action.



13. Remove the trigger. Punch out the small pin. Be careful not to lose the small spring.

I would like to say reassembly is the reverse but that is a bit of a cop out. Yes, it is the reverse order but the top lever spring/plunger and the locking bolt connecting rod spring/plunger are a real pain. The top lever spring is prone to flying away on you, so care required. EYE PROTECTION

14. Replace trigger. Set the spring (short side) on the trigger. Holding it in place with your fingers, place the two into the trigger cut out of the frame. This can be done easiest with the trigger approximately 90 degrees off its normal position. Insert pin. Move the trigger into the correct position.

15. Replace the firing pin and screw

16. Position the locking bolt and locking bolt connecting rod and top lever. Replace the top lever so that it fits between the two sides of the connecting rod and the end of the connecting rod rests inside the cut-out of the top lever. Now insert the bolt pin paying attention to the fluted end. You can insert by hand and ensure that the fluted end engages the fluted frame hole by rotating it until it grabs and won't move further. Tap into place with a brass hammer. Final placement requires a punch. Both ends of the pin will be proud of the frame metal. It will not have a flush side.

17. Drop the hammer from the top into place between the two sides of the locking bolt connecting rod. Align the hammer pin hole to the holes in the frame. Insert the fluted pin by hand and rotate until it engages the fluted frame hole. Tap into place with a brass hammer. Final placement requires a punch. Both ends of the pin will be proud of the frame metal. It will not be flush on either side.

Now we tackle the springs

18. Not quite reverse order but I found it easier to place the hammer spring assembly in position first. The hammer is loose now. Place the assembly with the plunger head engaging the hammer and the other end aligned with the hole in the frame. Pull the hammer back to hold the assembly loosely in place, ensuring proper engagement at both ends. Now pull the hammer all the way back and feel the spring tension. You will see pin punch or the small nail become loose. You can now remove the punch by hand or the nail with needle nose pliers. Allow the hammer to move forward under spring tension. While holding the hammer, pull the trigger to allow the hammer to rest in the full forward position. That one is done and relatively easy compared to the next two.



19. Replace the connecting rod spring and plunger. Note the two holes in the back of the frame. This group uses the top hole. The plunger has a very pointed end that engages into a small dimple on the locking bolt connecting rod. This now sounds easy but it is a real pain. EYE PROTECTION Place the spring on the plunger. This assembly is longer than the space available, so you need to align the rear of the assembly with the hole in the rear of the frame. Now you need to compress the spring and then push the pointed end of the plunger onto the connecting rod and move it into the dimple. There will be a satisfying click when that happens. The devil is in aligning the plunger while simultaneously compressing the spring. I found a small screwdriver blade inserted between coils of the spring could then be pulled back to compress the spring enough. Be prepared to be pissed off more than once while doing this.




20. Replace the top lever spring and plunger. This is the worst and most prone to flying away from you. Take a look at the back of the connecting rod. You will see a slot that is the width of the plunger. The plunger has to get into that slot. All you have to do is align the rear of the plunger with the remaining hole in the frame while simultaneously compressing the spring and pushing the front of the plunger into the slot between the connecting rod and the top lever. Easy right? NOT ? EYE PROTECTION.



You have now successfully disassembled and reassembled the components held within the frame of the 840. If you are an experienced gunsmith with tools I'm not aware of, you won't be reading this. If you are a tinkerer, you might find this useful. I could not find anything like this even with all those search engines out there so I'm paying back for all the times others have come to my aid.

Oh yeah, after you are done you can celebrate with beverage of choice - but not before. Be prepared to be annoyed and then immensely satisfied when you win.

Cheers,
Jack

I really suggest you download this on YouTube!
And/or a sticky here On SGW!
ether way ......nice work!

Thanks for that. I'm not sure how to go about a "sticky" and, while I have searched YouTube, I have no idea how to put anything on that site. Just an old guy here and technically challenged. Lucky to have figured out posting pictures.

Great write up!
I've got a model 84 (thats the pre-winchester model) in 20 gauge. The internals are identical.
It was my dad's. I plan on keeping it for a long time.
This link is bookmarked.

There were some home made fixes on this old Cooey. Two I did not take a pics of. One was holding the barrel to the forend with wraps of black electrical tape. The other was a home built forearm spacer made from some type of soft moulding material. It did take up the space but was not really functional. The screws were there but they made a real mess of the front of the frame because the moulding material eroded leaving the screw heads in contact with the frame.

Another fix was attaching a generic trigger guard. The rear screw used went too far into the action and the tip broke off against the hammer spring plunger bushing, leaving that small chunk of metal to interfere with the action. The front of the original guard just fits in place with no screw required. The front of the generic guard was drilled to allow a 1/4 inch bolt to pass through. This was secured by drilling and tapping the bottom of the frame. It worked but not a recommended course of action. This left a problem area to repair. I'm afraid I did not weld it up and grind and polish, which is probably the correct fix. I chose instead to make a screw and hold that in place with JB Weld and clean it up as best I could before re-blueing the frame.





Here is a hint for someone disassembling the forearm parts. The forearm catchplate has two tabs - one long one short. After removing the two screws, DO NOT just pull up on the front protrusion. This gun had the broken short tab still embedded in the wood. I tried to find a used replacement and noted the same broken tab on others. Finally did find a good part. To remove this piece, gently wiggle the front and then insert a small screwdriver blade at the rear and gently pry up. Unless you do this, there is a fair probability of breaking off the small tab. A broken small tab is shown in the second pic as well as the good part.




Lastly, the forearm and butt stock are from a Model 37a not the 840. The recoil pad is off some Browning gun and I will try to find a Winchester era Cooey plate. So, the gun is a compilation of parts to make a whole gun. Given that, I will just be making it look as good as I possibly can. I'm sure my friend will be pleased regardless. At least at the end of this exercise it will also be safely shootable. He is not a hunter, so I told him I will test fire it this fall for him during pheasant season. Cheers, Jack

Every Gun show I've been to (thats only about 5 shows total) has had an abundance of Cooeys as well as the Winchester-Cooeys for sale, I don't know exactly where you're located, but its likely the same where you are. There are usually a lot of guys who've got boxes of random parts too. Just about everyone in Canada had one of these things. If you need any parts, you're likely to find them there. Ask any guy thats got boxes of parts on their tables and bring what you've got thats broken if need be to compare. You're like as not to find what you need within a few shows.

Thanks so much OP! I am just beginning to break one down that has not been touched for a looongtime. Cant find much info on how to do it and though your writing rocks, I am green. Joined this site to get in contact with you as no one on CGN has answered in depth.

Could you please detail how to disassemble the ejector assembly?

Also, is it possible to convert it to an extractor?

Thank You!!!

Thanks for taking the time to produce this how-to. I recently purchased a Model 370 and will use this to properly disassemble and re-assemble after a through cleaning.

Excellent post for Cooey lovers everywhere, I still have a Cooey 84 .410 that was hard to cock but I bought a scapper 12 gauge with a lighter main spring and did a swap, I kept the spares and a nice walnut stock and I'm now looking for a better condition 12 gauge. I used to have a Winchester Cooey 840 in 20 gauge, it served me well and had a lot of hard use.

PS lots of Cooeys in the UK, mostly 12 g .410.

I have just bought a Cooey 84 in 12 gauge, I got it at a bargain price of £25 ($32.50) it is in very good condition except the forend was loose, I have tried to tighten the catch by tapping the barrel lug a few thou back but I think the spring and lug are worn and not making proper contact.
Anyone know where I can get a new spring and that will post it to the UK ?

Gamekeeper,
Check EbayUK. It looks like they have some Winchester/Cooey 84 parts.

Also, very good original post.

Thank you Wildwood, I have located a complete forend but I'm reluctant to buy it as it seems the root of the problem could be the forend lug on the barrel. I have filed a new profile similar to my Cooey .410, the forend now fits but again comes loose with shooting heavy loads. I may still require a new forend spring but for now I'm just reshaping the lug.

UPDATE.
Having nearly but not quite fixed the forend I bought the used one, although I thought it would be a waste of money BUT success, I swapped the wood over, as the original forend has nicer wood and it is now fixed.

Gamekeeper,

Good news on your update. Glad it worked out.

Great How-To post, thanks to the OP. I could see that replacing the connecting rod spring and plunger was going to be a real pita. Lining up the plunger with the hole and compressing the spring at the same time is the problem. So, I made up a spring compressor by modifying a $2.00 G-Clamp. The modification took ~15 mins and the installation took < 30 secs. I hope this helps.

OP here. I am amazed at how much interest this topic has generated including PMs. Now the c-clamp trick. Thanks for that. I will be adding that to my odd ball tools. I have done a couple more 840s and that spring is a pain. Thanks for the suggestion. Cheers Jack