The thread title is pretty self explanatory. I'm looking to do a chamber casting of my Browning A-Bolt Stainless. I've read about them but never seen one. Anybody here know of a good way to do it? I imagine I could melt some soldering flux, but that would take a lot of flux but I don't think it would be good for my chamber and it would be a PITA to get out.
You use this stuff. Cerrosafe.
This is from one of their Tech pages.
Hints For Using Cerrosafe
by: Mike Watkins
Recently, we’ve fielded a lot of questions on the Tech Help Lines about casting chambers using Cerrosafe casting metal.
The following is some information about Cerrosafe that Cerro Metal Products has provided us with.
1 lb. Cerrosafe Ingot
“The basic ingredient of Cerrosafe is bismuth. Bismuth is a heavy, coarse, crystalline metal which expands when it
solidifies, up to 3.3% of its volume. When bismuth is alloyed with other metals, such as lead, tin, cadmium and indium, this
expansion is modified according to the relative percentages of bismuth and other components present. As a general rule,
bismuth alloys of approximately 50% bismuth exhibit little change of volume during solidification.
Alloys containing more than this tend to expand during solidification and those containing less tend to shrink during
What all this means for the gunsmith is that you can make chamber castings using only Cerrosafe and a few, simple hand
tools. To make a chamber casting, first clean and degrease the chamber. Use a tight-fitting, cotton patch that’s wrapped
around a bore mop or brush to plug the bore just ahead of the throat. I usually leave the cleaning rod attached to the plug
until it’s time to remove the plug. Melt the entire bar of Cerrosafe in a heatproof container that you can easily pour the hot
Cerrosafe out of. You can use a propane torch or heat over a hot plate or the burner of a stove. Cerrosafe melts easily at
158°-195° F. While the casting metal is still liquid, stir very well, skim off the dross and pour your chamber. The real trick
with Cerrosafe is not to overheat it. If you heat the solid slowly, and keep it within the required temperature range, you
shouldn’t get any dross.
Note the time the casting was poured. The casting will take only a very short time to solidify, usually within a minute. Wait
30 minutes and then remove the plug from the bore. Turn the muzzle upward and the casting will fall from the chamber. At
30 minutes after initial solidification, Cerrosafe shrinks slightly, so removal is very easy. Allow the new casting to cool
thoroughly then measure the casting exactly one hour from the time it was cast. The casting will give you an exact
measurement of the chamber. Cerrosafe casting metal can be used over and over. Remelt the entire amount back
together and pour the Cerrosafe into a small mold of the appropriate size. Always melt the entire Cerrosafe ingot to make
a chamber casting. For best results, never cut off, or use, just a part of the ingot.
You use a special low-temp melt metal known as "Cerrosafe" chamber casting alloy.
Among other places, you can buy it at Brownell's:
Cerrosafe. #080-027-050. $12.00 per 1/2 pound.
This melts at 150 to 190 degrees.
To use, coat the chamber with a thin coat of oil or graphite.
Make sure the barrel is not cold, but NOT hot either, just about room temp.
Plug the bore just ahead of the chamber with a small rag that isn't so tight it can't be pushed out. Melt the alloy with a CLEAN iron ladle, then immediately pour it into the chamber.
For best results use a tube to pour the Cerrosafe into the front of the chamber first, moving it out as the chamber fills.
Wait about 30 minutes for the metal to cool to room temp, then push the cast out with a cleaning rod. DO NOT allow it to stand in the chamber for longer than necessary or it can be hard to get out.
Allow it to cool for ONE HOUR total. THEN measure.
Cerrosafe shrinks during the first 30 minutes after casting, then expands.
After ONE HOUR it's exactly chamber size.
It continues to expand, reaching .0025" LARGER after 200 hours.
The fact that Cerrosafe first SHRINKS then expands, allows it to be removed from the chamber.
Cerrosafe is re-usable.