Stiff Yugo M48 Mauser Bolt on Open and Close

OverTheTop · Aug 1, 2017

Not sure if this is the correct thread to post, but as the title says I have a Yugo m48 which has a very stiff bolt when opening and closing.

I have tried applying lubricant, in this case a very light layer of grease, to any surface which mates with another and have still been having issues. Interestingly when the safety lever is engaged the bolt will cycle very smoothly, which makes me think the threads between the bolt and bolt sleeve are binding when under pressure from the spring, but I'm not positive.

Anyone have some suggestions on possible cause and fixes for this issue?

willtill · Aug 1, 2017

I have a Turkish Mauser that does the very same thing. Haven't been able to figure it out.

Subscribed to thread...

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OverTheTop · Aug 1, 2017

Well I'm glad I'm not the only one with this issue.

Melnic · Aug 1, 2017

Does it feel the same with and without a cartridge? (keep it safe bro)

OverTheTop · Aug 1, 2017

Melnic said:
Does it feel the same with and without a cartridge? (keep it safe bro)

It's been a while since I tried cycling with a cartridge, but I think it did feel the same either way. I'll give a try after I get off work to see if it does, and I'll let you know. I also have snap caps so I'll give it a try with and without the safety on, to see if there is difference.

Melnic · Aug 1, 2017

Well, if its stiff w/o a cartridge, that is a clue to what you can eliminate as the cause.
The point at which it becomes stiff is also another clue. Hard to push all the way forward?
starts to become stiff as you turn the bolt down at what point?

iH8DemLibz · Aug 1, 2017

Sounds like the final fit of the lugs is a little too tight. Is the bolt original to the rifle?

Came across this when I replaced the extractor claw on my 1916 Spanish Mauser.

Tight as could be when I first installed it. But with MANY blackenings and rub mark removals, it's slicker than snot now.

PS: The bolt shouldn't cycle at all when the safety is engaged. The bolt is only movable when the safety is in the upright/middle position. For when you're going to remove the bolt for disassembly.

Doco Overboard · Aug 1, 2017

Could be Fp spring is wrong for coil count and is binding in the body or the bolt shroud. It could also be insufficient sear cocking pieces ledge engagement and plus minus tolerance in the bolt shroud release plunger. Check it out to see if it is burred galled. Mauser bolts have a sloppy fit and there's a couple thousands clearance in there already with a stripped bolt. If there is not much difference between loaded or not that rules out a cHS problem and a tight extractor collar or poorly fit extractor can cause heavy bolt lift like what was already posted. Dont expect to much of a oiled like glass action in M48. I have had a few where heat treating had slightly warped the body but were smoothed up ok for general use. Coat the stripped bolt with dye-chem and work it to see where interference may be happening and work it out from there.

OverTheTop · Aug 1, 2017

Melnic said:
Well, if its stiff w/o a cartridge, that is a clue to what you can eliminate as the cause.
The point at which it becomes stiff is also another clue. Hard to push all the way forward?
starts to become stiff as you turn the bolt down at what point?

Typically the bolt cycles smoothly moving back and forth into battery. It's stiff when trying to rotate the bolt closed to the firing position or when trying rotate the bolt open to eject and chamber another cartridge. When rotating the bolt to open, whether the bolt is cocked or not, it requires a good amount of leverage, but it doesn't require an additional tool to open it as if there were a stuck cartridge. Its kinda hard to explain without physically handling the rifle.

OverTheTop · Aug 1, 2017

iH8DemLibz said:
Sounds like the final fit of the lugs is a little too tight. Is the bolt original to the rifle?

Came across this when I replaced the extractor claw on my 1916 Spanish Mauser.

Tight as could be when I first installed it. But with MANY blackenings and rub mark removals, it's slicker than snot now.

PS: The bolt shouldn't cycle at all when the safety is engaged. The bolt is only movable when the safety is in the upright/middle position. For when you're going to remove the bolt for disassembly.

It does have a mismatched bolt, but I don't think the issue is with the lugs. When the safety is in the upright position, the bolt cycles fine. If the lugs were slightly too big there should still be resistance when cycling without the spring pressure being applied to the cocking piece.

This is also my first Mauser, so I didn't realize the safety in the vertical position was not the official safe position.

JTH20 · Aug 1, 2017

I had a similar issue with my m24/47, but it was only when extracting a round. Turned out that the chamber had a thin layer of cosmoline and it would heat up when I fired it, and then make the spent brass stick.

I know it's a dumb question, but have you tried dissambling the bolt and giving it a good cleaning? Cosmoline is a bitch to clean and can get stuck in every crack and crevice.

Doco Overboard · Aug 1, 2017

Look at the cocking ramp ledge in therear of the bolt body. If it's galled or rough it may not work as well on the cocking piece. Have look at the threads on the bolt shroud for damage as well. Remember a Mauser 98 cocks on opening and the action needs to be worked smartly through the bolt manipulation process. It's a pretty robust design but you shouldn't have to beat the bolt open with a mallet either. Strip the bolt and look at the FP safety stop shoulders too. Some times they get beat up from getting worked against the mating surface in the bolt well. Bolt sleeve lock plunger could be the culprit too. Especially if the assembly is from the original bolt. Becuase the lock plunger indexes with the with the safety slot machined into the rear of the bolt body. When the bolt closes the plunger is pushed back all they way by the receiver and allows the bolt to close smoothly when operated.

OverTheTop · Aug 3, 2017

Alright to resolve this thread, I have tracked down the cause. I had thought the front locking lugs were lubricated, but upon further inspection they were bone dry. I applied some grease to the rear face of the lugs and the bolt cycled smooth as butter, well at least for a Yugo Mauser.

Thank you for all the suggestions all.

Doco Overboard · Aug 3, 2017

Good deal, don't forget the third lug or safety lug.

Cornelius · Mar 10, 2019

I recently bought a Yugo 48, I am in the middle of restoring/cleaning it. My bolt binds a bit towards the back of the action upon opening and closing. I've thoroughly cleaned and lightly greased the action and contacts, I just broke open the bolt and cleaned all of the cosmoline, lubed and reassembled it. Now the bolt is even harder to crack open than it was when it was PACKED with cosmoline. I gave it a good scrubbing and oiled it appropriately again, still harder to open than before. Any ideas?

BeoBill · Mar 10, 2019

Notice any rough spots on the bearing surfaces? Might need some stoning. Just a WAG. Since the bolt cycles I don't think it's the bolt internals.

Cornelius · Mar 10, 2019

BeoBill said:
Notice any rough spots on the bearing surfaces? Might need some stoning. Just a WAG. Since the bolt cycles, I don't think it's the bolt internals.

I combed over it, It's all pretty smooth. I'm at a loss, I will have to take down/rebuild the bolt again to make sure I didn't make a mistake, but it operates fine, just somehow tighter than before. I cannot understand why. If I get a rag and some Flitz and give it a good hand polish, do you think that will help my cause or damage the bolt? I don't really care a great deal about collectability with this rifle. I grabbed it to be a shooter.

BeoBill · Mar 10, 2019

I'd re-do the bolt innards again just to make sure. And of course, lightly lube while you're inside. If that doesn't work, I'll leave it to the brighter bulbs here for an answer.

buellsfurn · Mar 10, 2019

Doco Overboard said:
Look at the cocking ramp ledge in therear of the bolt body. If it's galled or rough it may not work as well on the cocking piece. Have look at the threads on the bolt shroud for damage as well. Remember a Mauser 98 cocks on opening and the action needs to be worked smartly through the bolt manipulation process. It's a pretty robust design but you shouldn't have to beat the bolt open with a mallet either. Strip the bolt and look at the FP safety stop shoulders too. Some times they get beat up from getting worked against the mating surface in the bolt well. Bolt sleeve lock plunger could be the culprit too. Especially if the assembly is from the original bolt. Becuase the lock plunger indexes with the with the safety slot machined into the rear of the bolt body. When the bolt closes the plunger is pushed back all they way by the receiver and allows the bolt to close smoothly when operated.

edit issue solved

BeoBill · Mar 10, 2019

What was it?

Stiff Yugo M48 Mauser Bolt on Open and Close

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