Smooth Mosin bolt hard to open after dry firing

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dakota.potts

New member
I just brought my Mosin home the other day. It's a planned project. The first thing I did was give it a mineral spirit bath and scrub (never touching those damned things again... impossible to dispose of).

The bolt opened up a lot smoother. In fact, I'd say the bolt is almost pleasant to move. Occasionally it will stick (I've noted there are loose tolerances on some of the surfaces and occasionally one will catch on the receiver if you push it a certain way) but if you handle it right, it will fly back and forth like nothing.

The problem comes after I dry fire it. I haven't put ammo through it yet so that shouldn't be a problem. After I fire it, it's nearly impossible to open. I wouldn't call it "sticky" per se. It's definitely a smooth operation, just an absurdly heavy one. Slapping it doesn't provide enough force. I have to hold the rifle sideways and lever it to pull the bolt up. Once it's pulled up, it will move back with almost no force.

I've heard people on other forums suggest that this is a cocking problem and I may need to polish some surfaces. I do have some sandpaper I can do this with. What surfaces are these? I've also heard that it could be a problem with the recoil spring or main spring.

Anyone have any experience with this?
 
Clean it really we'll it has cosmolone all over it and even just a little bit getting in there can make for a really rough or stuck bolt..my advice is strip it completely down and give it a really thorough scrub down..make sure you get in all the little cracks and crevices even the smallest amount can cause trouble
 
Other than that the mosin isn't exactly known for having the smoothest bolt operation ever it. An take a little extra force sometimes to open and close and close the bolt after you give it a good cleaning lube the bolt well..just remember if you are use to the buttery smooth action of a high end modern bolt action the mosin is not that and the bolt is a bit rough in function naturally..these where made to function and go bang every single time they weren't concerned with the soldiers having to put a little effort into working the action they just wanted them to work and be close to indestructible as possible
 
A couple of things I noted:

Even after a complete disassembly and mineral spirits soak, I missed a little bit of cosmoline around the trigger and chamber.

Pulling on the cocking piece while pulling the bolt makes it much easier to do.

As I worked the bolt (maybe 20 times) I noticed something odd with it. There are scratches appearing on the surface of the bolt, the side that sits up when the bolt is closed. It seems like there might be a burr somewhere that I'm not feeling.

With the bolt all the way to the rear, there is vertical play with the whole piece. It moves up and down as it rattles around the forward most part.

It exhibits resistance trying to remove the bolt.

Seems like another scrubbing and polishing is in order. Maybe ordering a lighter main spring. Any other suggestions?
 
Hmm if not any missed Cosmo then it could very we'll be a small but on the bolt or around the bolt..I'd say after another good cleaning just work the bolt repeatedly if there is a bur in there it will eventually work it's way out and smooth up with use..other than that have you checked the head spacing??i don't think would affect you operation of the bolt but it is still something quick and easy to do and is worth double checking..can you identify the exact area where the scratches are coming from??
 
Also as for the resistance removing the bolt make sure you keep the trigger pulled back until the bolt is completely removed if you let go just a little early it. Oils get hung up at the very end
 
Not sure of any other tools or ways to check its I'd suggest getting a cheap mosin kit..I think you can get them off amazon with the headspace tool oil can ammo pouch and a few stripper clips for pretty cheap..it really is something you should have and is very easy to use
 
Oh, is firing pin protrusion the same as headspacing? I checked my firing pin protrusion and it's about .080" (eyeballed with the tool) and passes the go/no-go test.
 
Yes sorry bad phrasing by me..if that is good then like I said I'd brake it down and give it all a good cleaning one more time then put it together oil the bolt and just work it a lot to see if it starts to smooth out..
 
I'm far from being an expert but when I read that the bolt was getting new scratches my first thought was that it's probably not the original bolt. A lot of the arsenal refinishes was just pulling parts out of bins and slapping em back together... maybe you're just wearing in a new bolt?
 
dakota, headspace is the distance from the face of the bolt to the front of the chamber. It's checked via two gauges: A "Go" gauge and a No-go" gauge. The bolt is supposed to close on the Go gauge, showing that the chamber is not too tight. If it closes on the No-go, it means too long in overall length, possibly allowing primers to blow out or for case-head separation.
 
You're cocking the firing pin when you're opening the bolt after you dry fire it.
Put a dab of some good quality grease (I've had good luck with Slick-50 wheel bearing grease) on the cocking cam part of the bolt.
 
dakota, headspace is the distance from the face of the bolt to the front of the chamber. It's checked via two gauges: A "Go" gauge and a No-go" gauge. The bolt is supposed to close on the Go gauge, showing that the chamber is not too tight. If it closes on the No-go, it means too long in overall length, possibly allowing primers to blow out or for case-head separation.__________________
Click to expand...

Art, does the Mosin use a rimmed cartridge?
 
Art, that's what I thought the headspace was. I don't have a set of go/no-go gauges, and those running around $50, is there another way I can check that? A set of digital calipers or something?

I have a quandary now. I took it apart, wiped out a lot more of the grease until it felt bone dry to the touch, and polished everything. I polished out the inside of the chamber and the bolt. I had a little surface rust on bolt pieces but I also wanted to generally polish everything up. It ended up looking pretty good.

However, it was very hard to finish the final part of the bolt re-assembly (pulling the cocking piece and rotating 90 degrees). I put it back in the rifle and since then I haven't been able to open the action. It's actually become more difficult for some reason after polishing :confused: Does that mean that maybe I had the opposite effect and left a burr somewhere?

If I could get it out, I would try greasing it.
 
Try cocking the gun by grabbing the bolt knob and pulling it back. Once cocked you should be able to lift up the bolt handle and open the bolt.

There is something wrong with the cocking cam surface of the bolt. Take the bolt apart and study how it works. You should be able to identify where the cocking cam is. It is the mechanism that converts the rotational motion into cocking motion, when you lift up the handle after firing. Make sure that cam surface is smooth. Lubrication helps but should not be necessary.

-TL
 
I'm ignorant about that cartridge. If it's rimmed, it headspaces on the rim, not the chamber.

Just guessing, checking the gap for a rimmed cartridge could be done by cutting 0.001" or 0.002" shim stock, and using a tiny dab of glue, stick to the case head and close the bolt. At some point, when the bolt feels snug, you know the clearance. But I've no idea of how much clearance there should be.
 
Plenty of videos online on disassembly of the bolt, here is one:

http://www.youtube.com/watch?v=Fl5zntBMruw

Review and make sure you re-assembled correctly.

The MN bolt is cock-on-open. So, when you inserted the bolt back into the action after reassembly, did it go in smoothly? You completed the insertion by rotating the bolt into battery, and dry-firing? And now you cannot open the bolt? Just confirming...

Try to put the bolt on "safe" by pulling back on the cocking piece, and rotating counterclockwise. That may free up whatever is hanging up. Then rotate it back into position with the top of the cocking piece back in the vertical position and try to rotate the bolt upward again.
 
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