M48A Yugo Sticky Bolt

[Calif-Steve]

Warm the chamber up with a torch? Ouch!!! Try the hot sun or perhaps a heat lamp. Torch will remove bluing. Likely it is merely brand new and needs break-in. Try to run the bolt 300-500 times. Try to gently break it in. Good luck.

Information

Warning: This is a relatively older thread This discussion is older than 360 days. Some information contained in it may no longer be current.

[WarPig1976]

Warm the chamber up with a torch? Ouch!!! Try the hot sun or perhaps a heat lamp. Torch will remove bluing. Likely it is merely brand new and needs break-in. Try to run the bolt 300-500 times. Try to gently break it in. Good luck.

Do it with every new purchase because I want to make through, short work of cosmoline clean up. I've never removed any bluing, burnt myself though... One can warm metal with a torch without burning it, after all what's the difference if it's heated by the sun, lamp, torch.

Ok, I'll say keep the torch 8' to 10' away as not to over heat the metal. Another way is to boil a pot of water and dunk the receiver in to get Cosmo out of every crack and crevice.

[Jack617]

I like the boiling water thing. I used it to clear the cosmoline out of my Mosin Nagant and it worked great. Thanks for the suggestions.

[Jim]

First of all, a question. Have you thoroughly cleaned it including breaking down the bolt?
Some may think that a silly question but over many years on forums, (I am a moderator elsewhere) I would have to say failure to have done so is the #1 most common cause of problems involving bolt, ftf difficulties.

Assuming you have broken down and thoroughly cleaned the bolt and receiver, let's consider other options.

I strongly urge you not to bring a torch anywhere near your rifle. It is not only unnecessary, it is potentially very dangerous to do so. Upsetting carefully heat treated steel is asking for trouble.
Bolts and like smaller parts can easily be cleaned of cosmo by boiling in water which will quickly dissolve cosmolene. The accumulated heat will not be sufficient to damage metal and will cause any remaining water in the parts to quickly evaporate upon removal from the water.
Spray can brake cleaner will also do wonders but, please, do wear eye protection. The stuff can easily spray back out at you!

For the record, I really doubt you have an M48A. Those are about as scarce as hens teeth. Yeah, you heard me right. The M48A was changed from the first model all milled parts rifle beginning in 1952 by the addition of one stamped part only; the floor plate.
Beginning in 1956, the M48 series rifle was manufactured for commercial export only and a major overhaul of the production line was undertaken to incorporate more stamped parts. This variation was dubbed the M48B. BUT, the modification from 1st model to one with stamped part or parts was satisfactorily identified to the Yugoslavs by the "A" on the receiver. They did not change the receiver ring stamp. The M48B continued to be stamped M48A.
Source, "Serbian & Yugoslav Mauser Rifles" by Branko Bogdanovic. Branko happens to be the Zastava (now owners of the arsenal factory that originally made the M48) company historian. He is also a researcher for Belgrade's Military Museum. He is also a widely published European author on things European military. He knows whereof he speaks regarding these. He also informs me that the M48A (stamped floor plate only) was considered the very best of the M48series and that Serbia is yet maintaining stocks of these as last ditch weapons. Thus the scarcity of them here.
the easiest way to recognize an M48B is by the trigger guard. The milled trigger guard/mag well is of course simple smooth steel. The M48B rifle's trigger guard/mag well is a welded up assembly of stamped parts. Most of that is concealed w/in the stock but, the trigger guard has a raised rib running around the outside of it.
Some images...
The 1st two from Left are full trigger guard/mag well comparisons, milled version on top. The second two images are of a stamped trigger guard. This is all that sticks out the stock letting you quickly ID an M48B. Another comparison is that of the mag follower. Again, milled on top.
Attachment 47514 Attachment 47513
Attachment 47515 Attachment 47516 Attachment 47512 Attachment 47511

There are some other stamped parts, most notably the "H-band" but these are the major ones and a complete list of changes has never yet been obtained.

This has gone on long enough but it corrects most of the errors. I'll post this before something happens to lose it! Then I'll post another reply offer some solutions...

[Jim]

Now, about that sticky bolt. If it's a used gun you got from somebody else as opposed to a surplus from military storage, it is just possible somebody shot Romanian steel cased ammo. This can cause a problem more commonly associated with Mosin-Nagant rifles which very often use such ammunition. I also know this because I shoot a lot of Romanian and can tell when I need to do a special clean.
These older steel cases are coated with a lacquer to protect the case. The heat and pressure of the case against the chamber wall can leave deposits of lacquer which can build up to the point of causing the bolt to stick and bind creating just what you are describing. Normal cleaning will do nothing for this because only one thing cuts lacquer- "lacquer thinner."
The trick in cleaning this is to get lacquer thinner a cleaning rod section and a chamber brush. You will want the action removed from the stock since it well may damage your stock finish.
Chuck up the cleaning rod section and chamber brush in a low rpm or variable speed drill. Dunk the brush in the thinner and start turning it in the chamber with the drill. Keep doing this while repeatedly dipping into the thinner. After a few spins try your bolt. When it moves freely clean the rifle chamber/barrel with a good gun solvent to make sure all traces of thinner have been removed and lubricate. Just do this when ever the bolt starts to bind.

Next.
Years ago when these were pouring in by large numbers this was a common problem. So much so it was called "sticky bolt syndrome." The actual cause was never satisfactorily found but a solution was. Best guesses as to cause were that the bolt was new and machine work a little rough or tolerances just a tiny bit off. Who knows. Anyway, the following usually solved the problem.
First and simplest...
First of all, make sure the bolt & receiver are thoroughly clean. Get some lapping or rubbing compound and coat the bolt & receiver's contact surfaces with it. Tape down the trigger and cycle the action about 200 times. This is a good time to fetch out one of your favorite war movies.

Secondly. This image is a little rough. Hey, it's old! It is mostly concerned with just smoothing up the action but has proven well for addressing sticky bolt syndrome too. I see it also references the break in method too.
Hopefully, one or more of these will solve your problem.
Attachment 47517