Chamber Casting Alloy
Sold By the IngotApprox 1 pound Rotometals Chamber Alloy (158-190) is the best known material from which to make a casting of the chamber and throat of a firearm to determine caliber or check the dimensions. It melts at a temperature just above M&M;'s, so all you need is a propane torch and a bullet casting ladle. It can also be used to make a cast of a dovetail slot or any other hard to measure area. Also, it is great for removing the front half of a case from the chamber, in the event of case head separation; and lots of folks cast a small portion of the barrel to determine bore diameter. For best results, measure the casting one hour after casting. Contains, (42.5% Bismuth,  8.5% Cadmium,  37.7% Lead,  11.3% Tin).Technical InformationBasic InstructionsPlug the bore immediately ahead of the throat of the chamber using a small cleaning patch.Pour the alloy directly into the chamber until full and allow it to cool, it will turn a shiny silver color. As soon as it has cooled enough that it is no longer a liquid (and doesn't present a burn hazard), remove it from the chamber. Take care not to overfill the chamber as the alloy will then run into the locking lug area, making removal extremely difficult.During the first 30 minutes of cooling cerrosafe shrinks. At the end of one hour it should be "exactly" chamber size.NotesMelts between 158 and 190 degrees FahrenheitShould be melted in a clean iron ladle without direct flame on the product.The chamber being cast should be cleaned thoroughly and a thin coat of oil or graphite applied.Contraction expansion factor versus time, measured in Inch per inch compared to cold mold dimensions.  Test Bar x x 10 2 minutes - .0004"6 minutes -.0007"30 minutes -.0009"1 hour + .0000"2 hours +.0016"5 hours +.0018"7 hours +.0019"10 hours +.0019"24 hours +.0022"96 hours +.0025"200 hours +.0025"500 hours +.0025"