Mosin Bolt - Sometimes sticky

[damosan]

So I have a Mosin. Cleaned her up good and took it to the range a few weeks ago.

I put 60 rounds through it and every once in a while the bolt wouldn't want to open. I didn't have to hammer it open but I did have to use more force than normal. The casings were fine. Showed no deformations, etc.

Last night I got a shipment of new (surplus) ammo (with a load of stripper clips) so I test loaded and cycled a few rounds. Stone cold the rifle would occasionally lock on a round but other times it'd be smooth.

Is the extractor biting too deep? Perhaps it needs buffing or I just need to put another 400-500 rounds through it to smooth it out "naturally." A buddy of mine says I should take a 20 guage brush to the bore and polish it up a bit -- if that was the case I'd expect every round to have issues.

Thoughts?

 

[=GoMango=]

You may have a little dried cosmoline or pitting in the chamber.
Try using a brush on the chamber.
Most likely it's just the Inconsistencies in comblock surplus ammo.

 

[niftyvt]

Take a good look at the chamber. I polished mine up with a drill (go slow please ) and a random shotgun barrel mop that seemed like it fit the chamber. I put a large patch over the mop and went at it for a while, then switched out patches. I kept at it until the patches came back clean, which took much longer than I expected it to.

 

[damosan]

Wouldn't a cruddy chamber affect every round cycled as opposed to one every now and then? I still plan to hit the chamber with a 20 gauge brush just to be sure.

 

[KMK1862]

Also check where the locking lugs of the bolt interface with the receiver. I've seen cosmo "hidden" there that can cause the sticky bolt.

 

[Travis Bickle]

Mine does the same thing. My friend said that its some kind of coating they put on the bolt and when it heats up (when you shoot or because its 100 degrees outside) it the coating melts and gets sticky.
I dont remember having a sticky bolt when I was shooting last winter, but maybe its because I didnt shoot as many rounds as fast as I did.

 

[damosan]

You may be talking about two different things there Travis. Either the cosmoline crudding up the works or the lacqeur they put on some of the newer 7.62x54r rounds.

For what it's worth the last time I took my mosin out I shot 40 rounds of old crap and 20 rounds of much newer stuff -- the newer stuff had no real issues at all. I plan to test some more Saturday.

 

[=GoMango=]

Also heard reports of lacquer paint depositing in the chamber when it's very hot and causing problems.
That's why I only shoot brass case or the copper washed stuff anymore.

 

[damosan]

Also check where the locking lugs of the bolt interface with the receiver. I've seen cosmo "hidden" there that can cause the sticky bolt.

Typically that's only after you've fired a few shots right? Once the old cosmo heats up and turns to goo. It'll do this in a cold rifle also?

I can cycle the bolt all day long and it works very smoothly without a bullet in there.

D.

 

[KMK1862]

Typically that's only after you've fired a few shots right? Once the old cosmo heats up and turns to goo. It'll do this in a cold rifle also?

I can cycle the bolt all day long and it works very smoothly without a bullet in there.

D.

If there was cosmo in there it'll stay there unless you get it really hot. I seem to recall seeing it if I looked down in the barrel from the breach end at just the right angle.

Depending on the size of your hand and fingers, I've used a large shotgun cleaning patch soaked in Hoppes #9 and tried to make sure I rub the patch through the locking recesses. If there's Cosmo in there it'll show up on the patch and even remove some of it.

 

[Travis Bickle]

You may be talking about two different things there Travis. Either the cosmoline crudding up the works or the lacqeur they put on some of the newer 7.62x54r rounds.

For what it's worth the last time I took my mosin out I shot 40 rounds of old crap and 20 rounds of much newer stuff -- the newer stuff had no real issues at all. I plan to test some more Saturday.

I assumed he was talking about cosmoline. But I got the cosmoline off pretty good. I think your right about the ammo, It didnt even cross my mind that they're lacquered.

Ive shot 2 boxes of new production stuff. I dont remember if my bolt stuck or not, but I do remember being unimpressed with its quality in comparison with surplus ammo.

 

[psoyring]

Watch out for the bear ammo, not only will brown bear give you sticky bolt due to the lacquer coating, but I have misfires with the stuff.

 

[j8064]

Sounds to me like a typical vanilla Mosin and surplus ammo issue. That reminds me to put the rubber mallet back in the truck under the back seat so it's always with me at the range when I take my Mosins.

You could make a science out of the sticky bolt syndrome of Mosin rifles. Could be chamber dimensions, could be cosmo, could be lacquer on the ammo...so on and so fifth. If the chamber is clean and the rifle is safe to shoot, sooner or later a round will stick the bolt a little.

But think about it. Millions of vanilla Mosins were manufactured. A gazillion rounds of ammo was built. The notion that every rifle or every round is perfect when the two come together is nonsense. Built for the masses, these are not precision rifles.

During WWII, thousands of Russian troops armed with Mosins were returning Nazi fire in battle. If a Mosin failed, no doubt there were plenty laying around they could pick up. Some of those rifle failures were likely stuck bolts.

Bottom line is, enjoy your vanilla Mosins for what they are...terrific pieces of history and fun shooters. And have a rubber mallet or a piece of 2x4 with you at the range.

 

[Machodoc]

Go to the local auto parts store and buy a can of brake cleaner. Then pull the bolt out, put it into one of your wife's favorite glass baking dishes, and hose the thing down.

Then pull the barrel and receiver off the stock and hose down the chamber and bore. Use a bronze brush on both, then repeat ... and again. Then blast the bolt out once more. If you know how to disassemble the bolt (and get it back together again), do that and blast all the parts ... let dry ... lightly oil everything, and put it all back again. Anytime I've had a "sticky" bolt, cleaning was the cure, and usually the chamber was the culprit. Don't assume that it's clean because you cleaned it and it looks perfect. The performance tells you that it isn't clean. Old coats of cosmo lurk, hidden, in the strangest places.

 

[Jimbob2.0]

Make sure you brush the grooves above and below the chamber good, in mosins a lot of cosmo lays there, its weird how much travel between the mag and chamber they have and it just eggs for a jam.

 

[JAGGUY]

My M38 does the sticky bolt thing only when shooting coated steel cased ammo.
With brass it never sticks so that's what I shoot...

 

[=GoMango=]

My M38 does the sticky bolt thing only when shooting coated steel cased ammo.
With brass it never sticks so that's what I shoot...

It is really like I said above "Most likely it's just the Inconsistencies in comblock surplus ammo."

One type of surplus ammo will work and another will not in any given rifle.

I have enough Mosin rifles where if I end up with ammo one rifle is not happy with I will likely find one of my other Mosin rifles that will shoot it without any trouble.

I have the least trouble with brass case "generally" but copper washed also works OK in most my Mosin rifles, but even then one type will work fine in a rifle and another may not.

 

[JAGGUY]

It is really like I said above "Most likely it's just the Inconsistencies in comblock surplus ammo."

One type of surplus ammo will work and another will not in any given rifle.

I have enough Mosin rifles where if I end up with ammo one rifle is not happy with I will likely find one of my other Mosin rifles that will shoot it without any trouble.

I have the least trouble with brass case "generally" but copper washed also works OK in most my Mosin rifles, but even then one type will work fine in a rifle and another may not.

You're correct. I should have said lacquer coated steel cased.
I have no problems with copper washed steel either...

 

[Sirex]

I took the action out of my stock when doing the trigger work, stopped up the muzzle with a earplug, tilted the rifle breech up, and sprayed some foaming engine degreaser in there. Let it sit, then used a 20G bore bruch in the chamber. Took the earplug out, sprayed carb cleaner down into the chamber, then rinsed with non chlorinated brake cleaner. Spotless. Also cleaned the bolt and buffed the lug contact surfaces with some 400-800 grit sandpaper and rust eraser. Super smooth now until laquer buildup.