Saturday, November 15, 2008
Time To Clean This One Up
My new BRNO ZKM 468 22 LR, a C&R treasure I picked up a few months ago and have only had time now to play with it.
It is a single shot training rifle manufacture in Czechoslovakia, it came with swivels installed. Some of the articles I read about it also called it a "garden rifle."
The two pictures above really do not show how poor the stock looks. Now don't get me wrong, dents and marks from use during it's previous life is acceptable. But the way the finish has been slopped on and the crud stuck in the finish is not.
The bluing is in good shape with some crud stuck in the corners from dried grease and oil. There are some pits in the metal under the stock. When cleaned, the stains on the in-the-white bolt were minimal.
The first problem with taking it apart, was removal of the take down screw which was very very tight. Finally with the aid of a 12 inch screw driver and a 12 inch crescent wrench the fitting unscrews.
Bummer, it has been cross threaded and its not really a screw. It is a cup shaped fitting with a screw slot that fastens over the end of a shaped bolt dovetailed into a fitting attached to the barrel. The shiny portion on the bolt identifies the cross threaded area that needs to be cleaned up for reassembly.
A close up of the cross-threaded bolt. Now I need to figure out how to clean up these threads for reassembly.
Right side of butt stock. The stock has been washed with 409, scrubbed with 220 sandpaper and very coarse steel wool.
Left side of the butt stock after some cleaning and being lightly worked over with 220 sandpaper and very coarse steel wool. The dark area in the butt stock does not appear to be a crack.
More to come, waiting on some feelers about the take down bolt.
Update: 20 November, 2008
It turns out the threaded bolt in question is metric and it may be M8X0.75. At least I have been told that is what is used on the present CZ550 rifle. Now I have to figure out where to get what I need to clean internal and external threads sized M8X0.75.
Update: 21 November 2008
You can not believe how unpopular a M8X0.75 thread really is. I may actually find some hens teeth before I actually ID the thread of this bolt.
Update: 24 November 2008
The adventure continues, here is the stock-bolt removed from the dovetail slot which attaches it to the barrel. The stock-bolt besides being of odd thread is also a one-of-a-kind shape to say nothing of the cap nut which actually secures the stock to the rifle.
In metric sizes, M8X1.25 is considered coarse pitch, M8X1.0 is considered fine pitch but there are it seems also two other rarer pitches which are M8X0.5 and M8X0.75.
So I have ordered a tap, a die and a thread restorer file in M8X0.75.
Update: 26 November 2008
The stock has been cleaned and steamed to minimize dents. It was then gone over with steel wool and scrubbed with Formby's Furniture Refinisher.
Update: 4 December 2008
The magical implements arrived yesterday. Of course they sat on the front porch because the deliverer didn't even ring the doorbell and no one uses the front door. But this morning while out doing my two mile walk I saw the package on the porch.
In a half hour, I had the stockbolt, end cap and a spring nut all cleaned up. They now screw together very nicely.
Also yesterday, I added another coat of Formby's Tung Oil to the stock and I touched up the bluing on the sling swivels, the trigger guard and some of the swivel screws. Some of the wood screws will have to be replaced so I will be out looking for them.
Updated 9 December 2008:
As you can see from this picture, the BRNO looks pretty nice. It is not complete yet. I still have to attach the swivels to the stock. The screws on it were old rusty wood screws. I found a place on line where I could order oval head black oxide wood screws. They are presently enroute. It turns out for the unknowing, black oxide is basically bluing.