What is Cerrosafe™ and How to Make a Chamber Cast.

Cerrosafe from 4D Reamer Rentals LTD

CERROSAFE™ alloy was originally made for toy soldier castings. One of its most popular uses today is casting to check gun chambers. Cerrosafe shrinks during the first 30 minutes and at the end of one hour is EXACTLY the chamber size. Some other uses are casting cavities such as threads, dies, molds, blind holes, duplicate patterns in foundry matchplate making, support work pieces while machining; spray coating wooden patterns, dental lab techniques, masks for electroplating. Cerrosafe is a non-eutectic alloy with a yield temperature of 162.5º F.

To make a cast, clean the chamber thoroughly and apply a very thin film of oil or graphite. Plug the bore immediately ahead of the throat with a small cleaning patch – but not so tightly it cannot be driven out. If possible, pour the molten alloy through a small tube into the bottom of the cast, gradually removing the tube as the chamber fills.  We recommend that you warm the barrel to just above room temperature before making the cast. When cooled, remove from chamber, using a rod or dowel from the muzzle end of the gun.
Cerrosafe shrinks during the first 30 minutes of cooling and then at the end of an hour, is EXACTLY chamber size. At the end of 200 hours it will have expanded approximately .0025″. This factor is known to reamer or die makers and they will take it into consideration when making dies, reamers, or gauges from your casting – just tell them the cast is of Cerrosafe.
Cerrosafe is reusable, and never wears out.  It provides excellent casts of chambers and will save you from costly guess work.  Identification of chambers is simplified by a clean chamber cast that you can measure and rely on.
Cerrosafe melts between 158° – 190° F. This alloy should be melted in a clean, iron ladle. Source of heat should be removed as soon as the alloy is completely melted, at which time it is ready to pour. Solidified castings should be removed from the chamber before, or when, it cools to room temperature. Cerrosafe should not remain in the mold more than an hour, as it will grip the chamber walls and be difficult to remove.
Just a few minutes work, for reliable results.

4D Reamer Rentals LLC sells cerosafe in 1/2 and 1 pound ingots.


Filed under ammo, Firearms, Gunsmithing, How To, Rifles, tools

3 responses to “What is Cerrosafe™ and How to Make a Chamber Cast.

  1. Pingback: Cerrosafe | Chemistry Blog

  2. Pingback: 8×57 (8mm Mauser) Headspace Gage | GunsmithTalk

  3. Pingback: Cerrosafe Properties, Uses, Precautions

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