Removing a stuck screw from a Mauser 71/84.

C

chasep255

New member
I just purchased a Mauser 71/84 which on the outside seemed like it was in great shape. The only issue was some pitting in the last 2" of the bore, but before that the bore was spotless. Yesterday I went to do a full disassembly to clean and inspect everything. My trouble began when I tried to remove the magazine tube. In most videos I found, the tube is supposed to slide right out. Mine however was stuck. Eventually I was able to slowly nudge it out using a rubber maillot and the end of a screwdriver. I could see why it was stuck. Although the inside of the tube was in good shape the outside of the tube was covered with rust which was kind of "gluing" it to the stock/receiver. I went at this rust with some steel wool so not I can slide the tube in and out with a bit of force but no hammer. Next I wanted to remove the stock. I went to unscrew the screw which holds the trigger guard to receiver. It would not budge and I did not want to apply too much force that I strip the screw (especially since all parts on this gun are matching and even the screws have serial numbers.) I then tried applying some penetrating lube to the screw head and letting it soak for an hour. This did not help. I then went out and got some liquid wrench and let that soak into the screw for an hour. This did not help either. Finally I brought it to the gunsmith at the store I bought it from and he worked on it for a half hour, brought it back, and said the screw was really stuck and corroded. He said he could drill it out and replace it, but since I have an all matching rifle I don't really want to do that. When I got back home I took the magazine tube out again and found that the screw ends right under one of the most corroded parts of the tube. I sprayed some liquid wrench there and let it soak but this still did not help.

I think what might have happened to this rifle is that someone had it out in the rain. They cleaned all the parts they could without removing the receiver/mag tube from the stock. This let water seep between the tight fitting metal parts and caused the corrosion. I am unsure what to do about this. I don't necessary need to get that screw out. I could just never remove the receiver from the stock. I plan on shooting black powder cartridges so I hope there is no fowling which gets under the part which lifts the cartridges from the mag tube to the bolt (not sure the correct term for this part.) I would also really like to clean out some the rust which is probably under there already.

Do any of you have suggestions or another approach for removing the screw?


This is an image from this page (http://www.militaryrifles.com/germany/71-84disassembly/71-84disassembly.htm) of the screw I am having the problem with.
MVC-123W.JPG
 
Penetrating oil, then use a flat blade screw driver in a drill press and apply downward pressure while turn the chuck by hand or with the help of a strap
wrench or pipe wrench.
 
Not to beat your idea, but it may bend the trigger guard in the shape of
a horseshoe. I have loosened screws too by tapping vigorously with a
light hammer...as in tack hammer.
 
A little heat might help.
It could allow the lube to penetrate better.
The safest way is to use a soldering iron on the head of the screw.
Worth a try.
 
This is what I would try:
Mix a 50/50 mix of kerosene and Dexron II (or III)
Put as much into the back side of the screw as you can.
Let it soak for a couple days.
Take a screwdriver that fits the screw well and tap on it while you turn it out.
You can use the impact driver (the kind used with a hammer) if you have a bit that fits the screw.
Take your time and if it doesn't budge then resoak it for a couple more days.

I have used this technique on steel exhaust bolts that were frozen and rusted in an aluminum head with great success. I use it as the only penetrating oil in my shop. It works better than anything I have ever used.

If you use heat then use a soldering iron on the head with the penetrating oil on the inside. The heat can sometimes draw the oil into the threads. Time is the key. It will take time to free the threads.
 
I would try some Kroil. Penetrates FAR better than other so-called penetrating oils, to include Liquid Wrench. Give it several treatments, allowing it to soak for several hours between each.

Put your stock in a vise (padded jaws, of course) and choose a screwdriver bit that exactly fits the screw slot. Grind the blade to fit, if necessary. Be sure to keep the screwdriver perpendicular to the floorplate; otherwise it's likely to twist out and damage the screw. Use a wrench on the screwdriver for increased torque. You may want to have a friend tap on the wrench with a metal hammer as you're applying pressure to it and the screwdriver. Don't know if the impact driver you've seen would be a good idea or not. I'd reserve that for the last resort if all else fails.

Good luck! Those old screws can give you fits! ;)
 
I worked on several old rifles that had the same problem. Kroil or other brews of penetrating oil should help, if it can make its way to the site of corrosion. That's a huge if in this situation. Applying the oil to the screw head won't do anything when the screw is stuck in the receiver.

I use impact driver. Most of the time it works. If it still doesn't budge, I know I have a real problem, and there is only one thing I can do. Drilling the screw out, that is.

I know people would argue against doing that to a all matched gun. But choosing between saving a screw from the drill bit and saving the rifle from corrosion, I need no further debate. I drill. I had to do that to at least two rifles. Sure enough, when I opened them up, they were all pretty badly rusted under the wood. All that penetrating oil I had put on the screw heads never got to the threads in the receiver.

-TL
 
Here is how I tackle a job like that. First I use a drill press. If you don't have one you can rig something, but try to get access to the real thing. NO, a hand held drill will NOT work!

Now get a screwdriver bit of the right size. You might have to cut up a good screwdriver. With a grinder/file cut the bit to a straight side bit (not tapered).

Now, chuck the bit in the drill press, and pad the drill press vise to prevent marring the stock. You may need a helper to hold the rifle at the right angle.

Lay the rifle in the drill press vise so that the bit can enter the slot at a right angle (straight down, not slanted). Make sure the bit goes to the bottom of the screw slot. DO NOT TURN ON THE POWER OF THE DRILL PRESS!!!!!!!

Carefully, bring the bit down into the screw slot and use the drill press handle to hold it in firmly. With the other (usually left) hand, turn the drill press chuck back and forth. Do not batter the screw; if it won't move, use some penetrant.

If the screw still won't turn, ask yourself if it really needs to come out!

Jim
 
So I think I am going to try the kroil / heat approach. If that does not work I will bring it back to a gunsmith who probably has a drill press and let him work on it. Thanks for the replies.
 
I am not convinced it is 'just me', but I believe the screws Mauser used to hold things were cheaply made, I have never found one that was strong enough to tolerate creative removal techniques and methods.

F. Guffey
 
Heat Kroil and time

Don't be in a hurry. Soak it down with Kroil then heat the screw with a soldering iron. Repeat that several times over the period of a week or so.

The drill press method works the best. Make certain you have a very exact fit of the screwdriver blade.
 
The drill press method works the best. Make certain you have a very exact fit of the screwdriver blade.
Click to expand...

I have never found a Mauser screw that that could take the torques, if it is stuck try anything before moving to the drill press. I know, it is nice to have all of those matching numbers; consider the 'leaver policy', leaver the way you found-er.

F. Guffey
 
stuck screw

one could try candle wax. get the screw hot with soldering iron get it as hot as you can without hurting anything candle wax will melt and most times will go where other solvents wont go. dont laugh i have seen it work on heavy equipment where nothing else did
 
Oil field operator technique

Oil field operator and maintenance techs use a back and forth (loosen/tighten) technique on large highly torqued flange bolts and nuts. I use a similar technique with a day's Kroil soaking and a battery powered Milwaukee impact driver - a little bit tighten and a little bit loosen until the screw/bolt/nut is out. So far no stuck fastener has defeated me nor has been marred by this technique. Key factor is a close fiitting driver head.
 
Oil field operator and maintenance techs use a back and forth (loosen/tighten) technique on large highly torqued flange bolts and nuts.
Click to expand...

Yea, I was working the floor when a chain came apart, the driller was 'bumping'. I will say this about the oil field, they know what a tension gage is and they know how to read one. And 48s, 48s come with pipes/cheaters, it is coming apart or they are going to bend the handle; or, they are going to crush the pipe.

F. Guffey
 
Floating chain

Hi Guffey

Sounds familiar.

Rig pusher offered me an opportunity to float chain. Naturally I declined because I did not wish to lose a finger and I am a geologist. This was on a rig circa 1982. These days chain is used on the smallest rigs and pipe tongs automatically release when proper torque is reached. Watched drilling operations on a Parker rig in eastern Russia and the operation methods between then and now have little in common. Automation, safety, comfort, control, etc. results in faster and more economical drilling.
 
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