Hello, I have a century arms M70AB2.  I have discovered that the dust cover release button on the receiver is missing the nut that holds it in place.  I know I can just pull the pin out, but I happen to like the button and find it makes it a lot easier to secure the dust cover back in place.  I was wondering if anyone knows where to get a replacement nut for that part, or what threading it is, so I can find a replacement at a hardware store or something like that.  Has anyone had this problem before?  If so, what did you do, other than simply pulling the button and spring out?  It must have came loose and fallen off during the last time I shot this rifle.  Thanks in advance.

The factory parts are hard to come by.  I see them for sale in forums or on Gunbroker occasionally (not often) but that's it.
Some people make them by rounding the corners off a metric hex nut and using a dremel to make a groove in the nut to tighten it.  Done with care, it looks pretty good when finished.
Take the cross-bolt to the hardware store with you and size it up, it's probably a 4mm or so.





Stake it or use Loctite on the nut so you don't re-live this again in the future.



 

Go to ACE hardware and buy (3) 5 mm x .8 cadmium nylon locking nuts (they are thicker than the regular nuts) in the metric section of the nuts and bolts located in the gray slide out trays.

Install one nut on the push button you removed from the receiver and screw it on but not so the nylon lock engages with the threaded portion of the push button (just so it touches it). Using a small bench grinder carefully grind off the six hex edges in the direction so the nut tightens on the push and does not spin off. Then carefully rotate the nut on the push button while grinding until it becomes round and fits it into the receiver hole and  has the proper clearance. Then carefully grind off the head with nylon lock (or it will be too long), and carefully using a dremmel cut off tool cut a slot on the end for a screwdriver to fit into.

Once everything fits properly and the push button engages and disengages properly when fit-checked onto the receiver, then paint it with a flat black paint of your choice. Using "Red" Loctite (I prefer the GEL) install it on your rifle and tighten until flush with your receiver.

The reason you need three nuts is; you will screw up the first one as part of your learning curve, the second one will get dropped and roll 20 feet across your garage not to be found until you move to your next house.

The installed one will be fine unless you by some luck find one somewhere, this will take 10 to 20 minutes to make or an unknown hours on the Internet locate one sometime in 2012 or jus leave it on.
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File a regular nut round. Cut a groove across it with a dremel. Apply bluing. Install with a notched float tip screwdriver and adjust until the latch works well. Then apply a tiny bit of green penetrating Loctite to it to hold. Done

Thanks guys, got some M4 locknuts.  Didn't have a dremel, so i used a handfile and a hacksaw, and painted it with an epoxy coat.  Looks about the same, does the trick!  On the other hand, these plastic handrails heat up so bad on this yugo, is there anywhere to find yugoslavian wooden handrails?  All I can find are the standard shaped ones.

Good surplus wood here:  https://www.apexgunparts.com/product_info.php/products_id/1132



They refinish nicely.




 
 

Ironwood Designs makes some terrific teak ones as well.

Just sanded and then a simple teak oil finish: