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Discussion Starter #1
I am getting this thing ready to go out and use it, but the previous one had mentioned he put 40 rounds through it and it kept Jambing.. so I got this thing apart cleaned it and lubed it up. Went over all the info I could find here made sure the parts are all good and not bent etc, made sure screw on bottom is half turn out, but for some reason I don’t know if this is normal but when I pull the charging handle back the bolt stays open, from everything I have read online and seen videos of it shouldn’t do that?
anything I missed to check or adjust?
99635
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PhD in Over-Engineering
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When the top cover is open, the extractor is not always following its proper path, and can hang up on the feed cam on the left plate. I realize that your pictures do not necessarily imply otherwise, but just want to confirm if the bolt sticks also with the top cover down and latched, not just when the cover is open. Also, your pics show the retracting bar is off, so I assume we can eliminate that as an issue. Try removing the drive spring assembly and see if you can feel any binding point in the bolt travel. The amount of breech lock cam float sometimes has an effect, depending on the gun. Some don't require any float, but it's one thing to look at, as you mentioned.
 

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Discussion Starter #4
Thanks for the reply. I will check the cam float again.
with the cover closed it does the same thing
While cycling it few times I did notice this.
the pin on the left of the extractor seems to get caught up on the left side plate and doesn’t always drop down..
is it safe to file down the circled area on left side plate?
99644

this is wherethe extractor is getting stuck.
99645

this showing the extractor pin stuck

99646

this is the pin on the extractor I am talking about.
 

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PhD in Over-Engineering
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Yep, that is exactly what I was referring to. That indent cut on the rear of the cam is there to deliberately secure the bolt open- via that plunger in the extractor assembly- when you are intending to work on the gun and need the bolt locked back. Kind of redundant on an M37, given the retracting bar can be used to lock the bolt to the rear as well. But, it's a standard feature. Now with your cover closed, the extractor should be guided well enough to not catch the cam, but slip under it. I'd be very careful about removing metal there. The cams are hard- or are supposed to be. Not sure what TNW used, as they used kits that were made up of many new manufacture parts. At most, maybe round the bottom corner a bit so there is no sharp edge, but you don't want to change the shape of the cam. It is a critical part of the feeding mechanism. Also, look at the plunger in the extractor. It should have a clean transition from the round profile to that flat on the top. Make sure there are no burrs that help it to get snagged on the cam. TNW got 50 new made M37 extractors from me, but they did the assembly from the parts I supplied. They probably had some original extractors too. I can't tell from your pics, but if there is no drawing number, no SAK or RIA marking, it's likely one of mine. They have never failed me.

With the cover open, it is common for the extractor to rise and catch there. Should't happen when the cover is closed. Make sure the top cover extractor cam (ramp) and the cover extractor leaf spring are in good condition, as those are what keeps the extractor on the path through the side plate cams.
 

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Discussion Starter #6
Yes with the cover closed it still does it.The ramp on the cover seems to be in good shape.. I don’t see any leaf spring on the cover anywhere..
99694
 

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Its there...just above the ramp and below the cotter pin....It's the part with the dob of grease on it...It looks a bit flat to me and might be your issue....M37 are new to me so I am just guessing.
 

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PhD in Over-Engineering
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I can see the spring I refer to in your picture, but can't see its condition. Sometimes they flatten out a bit and do not put enough tension on the extractor. Below is a pic to clarify the part I refer to. I should add, this is the same spring used in the 1917/1919, so it is commonly available.

100_6034 - Copy.JPG
 

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The M37 operates internally the same as the 1919 series. Try lubricating the gun ( looks pretty dry) and replace the spring.
 

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Discussion Starter #10
Thank you for the picture. Yes I see the spring there it does look kind of flat. Would I need a new one or can I pry it up a bit with a screwdriver?
99701


I have lubed it up.hard to tell in the pic.. it’s pretty greasy lol
 

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With the top cover open can you move the belt feed lever back and forth manually with ease? The feed slide assembly should move out and back in smoothly with very little resistance. Also, if the gun sat up for years without being fired I would replace all of the springs, very inexpensive and usually fixes some of the issues.
 

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Discussion Starter #12
With top cover open the feed can be moved with ease and is very smooth. All lubed up. The bolt slides very nice too up till it gets caught in open position.
yes gun has sat for some time. Where is a good place to get spring kit online?
 

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PhD in Over-Engineering
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All the springs are available from APEX, but I don't know if they have them packaged as a set. Sarco, has a set with the cover extractor spring and a few other good spares:

 

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Discussion Starter #14
Seems like it was the cover extractor spring.. took it out bent it a bit and now it seems to work very smooth.
thank you guys!
I also set the head spacing to two notches over full lock up, and used some foil tape to temporarily make a spacer for front cartridge guide since the ammo I’ll be using is shorter than the surplus. we’ll see how this thing fires when I finally get chance to take it out.I will order up a set of springs and spare parts but I don’t know if I’ll be able to get them since I’m in Canada and 1. The border is closed, 2. Hard to import any gun parts here.
Thank you guys again! So much good useful information on this site and so many good people!
 
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