Most of the time it'll cycle easily, I can keep it shouldered and gently cycle it as well or better than some modern bolts.

Once in a while, one round about every 2nd-3rd mag full it gets tight and needs a bump to unlock, the next round is back to smooth.

It's been cleaned thoroughly several times and I believe it's free of all cosmo.

I shoot surplus almost exclusively, don't recall if it's happened with modern ammo.

Any insight as to what I should look for?

Guy here at work actually uses a heat gun and brake cleaner to clean a new to him Mosin.  Heats up the receiver with the heat gun or hair dryer then sprays and scrubs it down with brake cleaner.  

While my Mosin sticks like crazy his seem to run really smooth even after heating up which is when mine gets much much worse.  I'm just too lazy to go through all that trouble for a rifle I shoot once out of 100 trips to the range.

bring rubber mallet with mosin to rangeski

Mine does the same and I am pretty sure its the ammo.  I have a can of 1970's ammo and it almost never happens with that.  I also have a can of 1950's vintage ammo and it happens much more often.  I am pretty sure some little old Hungarian lady used a tea spoon and a shaky hand to load that ammo.  Some sound normal, others noticeably lighter and then every once in a while a nice fireball.  It's usually those fireballs that cause the bolt to stick and some of those even split the case.  The fun of old ammo!

Chuck a copper bore cleaning brush for a 20 gauge shotgun onto a hand drill and remove your bolt.Use brush with drill everywhere your bolt touches careful not to hurt anything. Clean it again. This is for sticky bolt.
Take your bolt apart and clean it again. Clip off last coil and a half of your spring with wire cutters. I dremel it flat but you dont have to.
I have never had a round not fire and it really makes your bolt easier to use. This is for when your bolt is difficult to open even after its already cocked.

Pull back the cocking knob and cock it before opening the bolt, makes it much easier to open.

Hello,

Here you are:

https://www.youtube.com/watch?v=wVnx8_twi6M

I hope this helps ya'!

Regards,

Josh

Your issue doesn't sound like the common "Mosin sticky bolt" which happens as the rifle gets hot. Your issue sounds like it's ammo related. Try different ammo.

This.. fixed 2 mosins this way. I used a good chamber paste. Made chamber nice and shiny too. Obviously dont over-do it but once you see shine, you are probably done. Idea is to remove baked on chamber gunk and cosmo which prevents case from being pulled out.

Good luck.

I've run into this being the camming surfaces most times.

That vid will not embed for whatever reason, but those instructions should fix the problem.

Regards,

Josh

Thanks for all the replies.

I'm leaning towards ammo since it's a random stick.

I should have thought to examine the extracted shells to see if there was anything different about them, but didn't.

When I first got the gun I did a basic inspection then took it out.

It was a classic 'hammer cycle' Mosin, not as bad as some, but needed a handle bump to break free.

Then I did a more thorough cleaning after reading and learning about the Mosin and it got better, but still rough.

I then went to work on it; DIY trigger job (spectacular improvement), very thorough cleaning with multiple solvents and heat, lightly polished the chamber and friction surfaces of the bolt, then more cleaning.

My first lubing was a generic gun oil, don't recall which, felt ok.

I cleaned that off and went to tetra grease on the cam ramps, better, so I started shooting it.

Then I went to molybdenum disulfide paste, no good for fast moving parts, but perfect for high load slow moving stuff and it worked nicely.

Most recently went to FrogLube which I initially liked on everything I put it on but have found it turns to goo after a while and have started disliking it, their ridiculously priced 'solvent' acts like water with a little soap in it.

Frog has stopped many of my guns that ran fine before, the range fix was to squirt them with WD-40 or gun oil, whichever was on hand at the time, which fixed all of them.

This last trip I installed my .22 conversion slide onto my Beretta 92 and the Frog wouldn't let it cycle, I manually closed it several times and it eventually started running again without having to be oiled.

Leaving it in the sun I think kept it working, it ran every time I grabbed it from then on.

My Beretta .25auto has also been stopped by Frog, had to oil it to run, and I believe it may also be the cause of my finicky AR, once I finally squirted it with gun oil it ran great.

Frog even stopped my S&W .38, I Frogged the trigger/hammer parts and it slowed it so much it wouldn't pop primers, oil cured it.

I don't recall for sure whether the Mosin's problem started before or after Frog, but going back to petroleum will likely happen just to eliminate that possibility if I don't find another cause before getting to shoot it again.

When I tear it down again I'll go over the trigger to remind me of what all I did and post it up, everyone who's shot a stock one is amazed by mine and people who don't know Mosins say it's a nice trigger.

I appreciate the link, but found his video hard to watch.

When he stated talking about sanding down the connecting bar, where it bears on no other parts, I had to close it; this person doesn't seem to know enough about what he's doing for me to want to learn from.

Same opinion here.

If different ammo does not help look at the chamber where the rim makes contact. Look for nicks or burs. Look at the extractor also for a rough spot catching on the rim. Just a thought...

That got me thinking; should the extractor slide around the rim while rotating or should the shell rotate with the bolt face?

That's a good question. One I also thought about a few months ago so I checked it out.

I couldn't find any info on the interwebs about it so I checked things out with 3 different Mosins and their bolts.
I came to the conclusion that the extractor slides around the rim.

Out of 40 fired cases, not one had a thick enough rim for the extractor to grab onto and spin it around. There were some that were fairly tight and the extractor put scrape marks around the rim but it wasn't tight enough to spin the case if it was in the chamber.

Since coming to that conclusion I lightly broke the sharp edges of the extractor on my Chinese T-53 with a few light file strokes. It made a slight but noticeable improvement on the bolt operation. I no longer get scrape marks with light burrs on the rims even with rims that are thicker than normal.

I don't think that is the problem with the OP's rifle, though. With his I think it is an ammo related problem.
Even with all the work I've done smoothing and polishing every surface that rubs against another, trigger job, lighter springs, cleaning, etc. I still get an occasional round that sticks in the chamber and makes the bolt a little hard to open, just like the OP describes.
Olga probably just put a little too much powder in those.

Nothing you can do about it, I've tried.

OK, that's me.  No, I'm not photogenic.

I did not say anything about sanding down the connecting bar.  Polishing with 2000 grit wet/dry if it's rough, yes.  I assure you that I do know what I'm talking about, at least so far as Mosins and 1911s are concerned.  

The whole idea was about knocking off a very steep angle on the hammer camming surface that is not well fitted in wartime Mosin parts.

Please tell me how far in on the vid you misunderstood what I said so I can go take a look.  I tend to sometimes be as clear as mud and if I was confusing, I need to correct it.

Josh

Sounds like an ammo issue.

I completely disassemble any rifle I buy. I like to learn how it works and be real familiar with it. With my Mosins I did this and spent a long time cleaning it. I used mineral spirits first to remove the bulk of the cosmoline. Then I switch to acetone. After this I used a heat gun and brake parts cleaner until my white rags did not get dirty. Then I cleaned the bore with heat and brake clean.

After all metal was clean I then used bore cleaner and ran a few patches through. Then ran a bore brush through and followed again with more bore cleaner. Once I had them coming out spotless I oil everything and reassembled.

After my first trip to the range I was annoyed by how sticky and tough the bolt was to close.

I clean and then disassembled again and used some JB bore paste on a .410 mop and spun it with my drill in the chamber. Wow was that thing black and took a ton of effort clean all the stuff off. I then ran a mop with bore paste through the bore one time with my drill. That came out fairly clean so I would not do that again. After the bore paste in the chamber she works nice and smooth.

if you really think its ammo, then good luck since mosins eat anything.

As orhers and I have said, clean chamber with drill and paste. You are not going to hurt anything (unless you really over do it). "sanding" is the last word you should ever listen to in a forum post. It cant be undone and you have no idea who is posting the advice. The intermittency doesnt make it not a dirty chamber issue.. Whoever thinks that isnt thinking about marginality.

Meh...the expression "will eat anything" is usually reserved for self loading firearms. The sticky bolt issue is very repeatable, it starts as the chamber heats and stops when cool. When shooting surplus 30, 40 or 50 year old ammo you are starting at "marginality". To each his own I guess.

I'm not so sure about your conclusion.  The 'sticky bolt' issue so common with Mosins prevents the bolt from being unlocked, correct (thus the need for the mallet)?   If you get a gun warmed up enough that the bolt sticks, it only does so with a round in the chamber.  Once you get the round out, the same hot gun will hand cycle all day long on an empty chamber, or at least that's my experience.  That indicates to me that the extractor is holding onto the case so tightly that it won't allow the bolt to rotate at all.  Hitting the bolt handle with a rubber mallet is either a) breaking the case free inside the chamber, or b) causing the extractor to slip on the rim so that the bolt can pull the case directly rearward.  I could be wrong, but that's my take on it.  

I battled a 'sticky bolt' on my first M44.  Cleaned the gun a half-dozen times and still every time I got shot it it would stick after it got hot.  I took it home from the range more than once with a spent cartridge in the chamber.  Finally, a buddy handed me a box of (I think) S&B brass 7.62x54R and my gun ran flawlessly.  Turns out that the surplus ammo I was shooting was (again I think, but it's been a few years) the Bulgarian lacquered stuff.  The lacquer was melting in the chamber and sticking the case to the chamber walls.

The slow pace made it hard to watch right from the start, the misinformation sealed the deal.


As for the connecting bar, you suggested using 600, 800, or 1000 sandpaper on it across the inside and state that this will smooth up the action--this part doesn't bear on any other parts during operation therefore smoothing it will do nothing but change it's looks.

I guess it could possibly strengthen it to some degree if done right, but that's grasping for any useful purpose and not a concern anyway.


Your theory about the slop in the bolt helping lockup seems flawed.

If the lugs are uneven and the bolt rocks to one side so both locks engage then the bolt face isn't evenly supporting the case base.

Even tho neither condition is likely to cause a problem assuming the lugs aren't way off, I don't see the advantage to having it loose and if I had to choose I'd opt for even support on the case.

Even if all the pressure was on one lug it's unlikely to fail and if it does the other lug is right there with the handle as a back-up to prevent the bolt flying back.


The ball grease you said appears to be lithium grease but to keep it away from petroleum products; lithium grease is a petroleum product as are the few ball greases I've seen, says so right on the label.


Using anti seize as an abrasive for wearing in the cam surfaces?

While there are many formulations of anti seize products, none of them are abrasives and each has differing lubricating qualities.

Anti seize is a lubricant and could be described as a two stage lubricant--I'm sure someone more knowledgeable can paint a better picture but I'll give it my interpretation.

At low temperatures, below about 400F the grease is the lube.

When temperatures exceed the grease's ability to stay the fillers become the lubricant and these fillers are all much softer than the bolt cams so even if you somehow exceed 400F and/or the pressure limit of the grease you still have a lubricant.

Anti seize is also a great rust preventer tho I would caution to consider the type used and the conditions as I see a potential for interaction between metals.

The zinc based types should give passive and active protection to most metals if electrolysis is an issue at all.


If you want an abrasive compound use one; I've used lapping compounds and rubbing/polishing compounds on actions and both do a pretty nice job of fitting the parts to each other while polishing them.

Lapping compound seems to work better but rubbing compound is more commonly found in the average guy's garage and it'll do if one doesn't want to go shopping.


So many things I saw/heard in your video indicated to me that you don't know what you're talking about whether it pertains to the firearm or the products being used on it.

I'll take this one at a time to try to show where I'm coming from:












The bottom of the connecting bar has a groove in it.  The top of the trigger rides in that groove.  Smoothing off the machine marks from the top of the trigger and from the inside of the groove on the connecting bar does indeed improve the feel.  More on wartime Mosins, less on others.





The top side of the connecting bar bears against the bolt when the bolt is turned to lock or unlock.  Again, a bit of smoothing with wet/dry improves feel.





You might try some contact fluid to check this out for yourself.





 

I see where you're coming from.  My point was that bolt misalignment (in
which the lugs are integral to the bolt) effects the bolt lugs much
less because the bolt head is a separate part and has some wiggle room.
Yes, the lugs still need to be square to the face.  That was never the
issue I was addressing.  Again, you might see about some contact fluid
on the lugs to see how contact is made.  I think you'll be surprised.
The backup lug is at the handle base, like the main lug of the Berdan II rifle.





 

You may be right.  White lithium is a mineral oil suspension in most
cases.  It doesn't break down per se, but it does sort of get displaced,
diluted.  I should have chosen better wording.    Anymore, I just use
engine assembly lube for when I need thick lubrication.  The stuff
sticks and is pretty great when a heavier oil can be tolerated.

Traditional anti-seize is a mild abrasive.  I like to use it after using
2000 and 3000 grit.  It's made up of calcium oxide, graphite, and
aluminum powder in a suspension of mineral oil and other petroleum
distillates.  As traditionally used, no, it's not an abrasive, but when
you start talking moving parts, it does become abrasive.
There's a lot of debate if you Google "anti-seize as abrasive."  Put some on a mirror and rub it with a cloth for five minutes.
I do agree that rubbing compound is likely better.  Most folks around
here, anyway, have anti-seize and don't have rubbing compound.
I have a spare connecting rod that I'll send you if you care to try these methods.  
Regards,
Josh

To do the job really well, wrap the brush with 0000 stainless steel wool.  I have also used this trick on my Remington 870.  The newer steel hulls tend to stick a bit.  FWIW,  It ws not just Msin Nagants with this problems, but some of my milsurp Mausers needed the same treatment.