7.62/54r steel cases ammo locking up

[QUON]

I have 5 91/30 moisins that will lock up the bolt after firing military steel ammo. The model 44's gives no problems with the same ammo. Firing brass cases in the 91/30 is ok. No jamming of the bolt. Any one out there have this problem?

[bart55]

Prettty common with alot of the old mosins ,usually I find that its old lacquer from the steel cases that gum up the chamber ,doesn t seem to bother the brass thoiugh. I bronze brush that fits the chamber chucked in a drill with any appropriate solvelnt (eds red ,hoppes, or even kerosene ) run it back and forth and then I usually polish the chamber with a patch wound around the brush and coated with jb bore paste and finish with flitz polish . It worked on a couple of 91/30 's that I have . the steel ammo then works ok . without having to hammer the bolt open

[badbob454]

when i bought my m 44 ,it would not open on firing the brass cases.. returned the gun to big 5 sporting store , and had a spent case .asked to try it in some other mosin guns ... 4 out of 5 locked up , a little after dropping the firing pin on them . the one that didnt , i took home ..... , im no gunsmith , so i didnt know what to do ,otherwise ,, problem solved ,

[Storydude]

Get a 45 cal brush, section of rod that will fit in a drill and a drill.

Put brush in chamber with some oil/hoppes/ed's red, chuck into drill and spin it in chamber for about 5 min.

Google "mosin sticky bolt" and you'll find enough info to solve it.

[ilcop22]

In any firearm where lacquer ammo is being used, cleaning of the chamber is absolutely necessary. +1 on Storydude's recommendation.

[Multigunner]

Often jamming can have more than one cause. A sticky chamber might not lock the action up by itself, but if coupled with locking recess setback and stiffness of the sidewalls of the fired case a minor drag caused by multiple sources becomes a total lock up.

Ordinarily theres a tiny amount of locking lug bounce back when pressure drops. The amount would be extremely tiny and not measurable.
This bounce back acts to loosen the grip of the expanded case walls on the chamber. A slight contraction of the brass case is also expected. Steel cases may not contract as much after firing. These phenomena are vairiable according to many factors. Stiffness of the action type , recovery from compression of the alloy the action body is made of, quality of heat treatment, etc.
Military ammo usually has a staked primer, this negates the cushioning effect of the unstaked primer of commercial sporting ammo or handloads. The milspec case expands fully without resistence from the trapped gases of the primer forcing the primer back and exerting around 600 to 900 PSI on the inside of the case head.

Excessive drag of the firing pin retraction camming surfaces is another factor to be looked out for, especially in rearsenaled Mosin Nagants or those with new old stock replacement bolts.
A friend had an old TULA with the stiffest bolt of any rifle I'd seen before or since. While it never actually locked up, the bolt was so hard to turn you'd sometimes have to beat on the knob with a block of wood to get it to open, and that was with good ammo.
At first we figured it was a too stiff firing pin spring and cut two coils from it. This made absolutely no difference.
I then examined the cam surfaces, and saw that only the edge of the surfaces were making contact. The hardened edge was digging in like a saw. Both surfaces were rock hard so it wasn't wearing in.
I applied a tiny ammount of valve grinding compound to the cam surfaces, then worked the bolt half a dozen times. I then carefully cleaned the bolt and receiver to be sure not a spec of the valve grinding compound remained. After that the action was as smooth as silk.

[870TC]

As others have said, clean the chamber. Or try putting a drop or two of oil on one of the cartridges before you fire it.

[3006guns]

One more possibility.....is the chamber smooth and polished? I have an SKS that I rebarreled, but the bolt would not fully go into battery. I took it to my smith and he used a chamber reamer to take out "just a touch" until the bolt went home. Good to go.......almost.

The gun fires brass ammo beautifully but put in one steel case round and that's the end of the firing session. The bolt cycles but leaves the case in the chamber (the extractor rides over the rim) and it has to be smacked out with a cleaning rod.

Upon examination, the chambering reamer left tiny marks....just enough to hang up the steel case, but the cooperative brass just slides out. I'll be taking it back for a quick chamber polish.....no charge.

[Gtek]

I think you want to CLEAN, not polish chamber. There is a thing called case thrust which can go to ugly. Mosin bores are sometimes not .311, some way bigger, some a little smaller causing an increase in pressure which can also cause hard bolt lift. Finn's are sometimes down to almost .309".
06 guns- have you confirmed case dimensions, ie length and shoulder. The com-bloc stuff was manufactured all over that part of the world and it is not always the same in charge weight or dimension. Be safe-Gtek

[tomme boy]

The ammo is the problem. It is made for a MG not a Mosin. The Mosins are a last ditch weapon. The Russians dont care if you have to beat the bolt open. Some one else will pick up the gun and use it. They never threw any gun away. And let me guess the ammo is the Silver tip. The steel is not elastic enough for the bolt action rifles. I have been telling everyone that will listen this for years. People are just now starting to listen.

[Phat Man Mike]

I just took some hopes on a brush and cleaned the film of cosmo out of the chamber and it works fine. no hammer or liter of tater juice needed.

[dbldblu]

I bought some Russian steel case .223 ammo to shoot in my contender. The first and subsequent rounds were so hard to extract that I bent my extractor.

[NuJudge]

I have several Mosin rifles of different patterns. The Finnish M39 I have is the only one that extracts smoothly with steel-cased ammo. Brushing and solvent have not helped with the others. Brass case ammo works beautifully with all of them.

CDD

[QUON]

Cleaned and polished all the chambers. Brass cases ejected with no problems. The steel cases still need the bolt to be hammered up and back. Must be machine gun ammo. Thanks for all the input.

[303Guy]

I think you want to CLEAN, not polish chamber. There is a thing called case thrust which can go to ugly.

I have a different view on this. To me the purpose of the bolt is to support the fired case and that means to carry all of the thrust.

The problem with cases grip on chamber walls is that the case gives way suddenly, allowing the case base to fall back against the bolt face increasing bolt face thrust. This happens while the case neck and shoulder are still firmly held by the chamber walls. The end result is a case that can stretch non-elastically and lock up the bolt (insufficient spring back).

If it were me (assuming those were not machine gun rounds and if they were I would dump them) I would lube the cases to reduce (but not eliminate) case to chamber wall grip.

I stress that it's what I would do, not what anyone else should do!

[plmitch]

I have a couple of 91/30 moisins and have never had any problems with any surpuls that I have tried.