Creating a Chamber Casting

The following is an extract from "The Handloader's Manual of Cartridge Conversions"

by John J. Donnelly

Chamber casts have been made in the past from lead, linotype metal, sulfur and plactic compounds. Lead and linotype have unreliable - and usually unknown - shrinkage characteristics. Sulfur is somewhat dangerous to melt; it's also messy and the casts are very brittle. Plastic compounds tend to warp. The best material for chamber casting is low temperature melting point alloys, called fusible alloys, and the best of these is cerrosafe, specifically a variation called Alloy 158. This inexpensive metal melts at 158 degrees Fahrenheit, well below the boiling point of water, and it is reusable.

Creating a Cerrosafe Casting

To create a chamber cast, the weapon must be held in a vise, or some similar device, with the chamber in a vertical position, muzzle down. Clean the chamber - first with a solvent and brush, then follow with a light coating of gun oil. Use a cleaning rod to position a piece of cotton or some other fabric approximately 1" below the chamber. This will act as a dam to contain the metal.

Use a hair dryer, direct hot air on the barrel in the chamber area. Meanwhile, melt the alloy in a water bath (do not heat the metal directly or the metal will destroyed). Once the chamber area is warm and the alloy has melted, the alloy can be poured directly into the chamber, filling it to the very top. Do not add any excess; it will only have to be remove later. Now wait about one hour until the cast has cooled to the ambient temperature. Most fusible alloys expand slightly as they cool. This expansion will disappear when the cast cools, but not before. Do not try to remove the cast before the hour is up; otherwise, you may damage the weapon and the cast.

Once coled, the cast is easily tapped out with a cleaning rod. You now have an exact reproduction of the chamber and should be able to make accurate measurements of the casting.

Creating a Sulphur Casting

The following is an extract from "The Home Guide to Cartridge Conversions"

by George C. Nonte, Jr.

... Several casting compounds are available from industrial supply houses under a number of trade names. Simplest, though, is still probably the time-tested sulphur cast made up from materials you can pick up at the corner drug store.

Mix four ounces of sulphur with a pinch or two of lamp black and a teaspoon full of camphor dissolved in alcohol. Melt this mixture ever so slowly over a low heat while stirring constantly. When it reaches the consistency of thin cream, it is ready to pour. First fix a slightly over-bore diameter cork on the end of a piece of stiff wire. This wire should be long enough to protrude well beyond the receiver. It will serve as a handle when removing the completed cast. Push the cork into the bore about half an inch ahead of the front of the chamber. This will allow the cast to extend into the bore far enough to determine barrel diameter.

Now clean and oil the chamber carefully with a thin coat of light oil, clamp the rifle in your vise, muzzle down; and pour the sulphur mix in until the chamber is completely filled. Be careful so as not to get any overflow into the receiver recesses. When the cast has cooled, insert a cleaning rod from the muzzle and carefully push the completed cast out. Hold on to the wire handle and avoid striking the cast against anything as it is very brittle.

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Last modified: 23rd October 2008