Making Cerrosafe Chamber Cast
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Thread: Making Cerrosafe Chamber Cast

  1. #1
    Join Date
    Oct 2010

    Default Making Cerrosafe Chamber Cast

    Have attempted several times to make a Cerrosafe cast of the chamber in my 91/30 to examine the chamber for damage/erosion and to tell where the lands start for bullet seating during reloading. Cannot get the chamber cast out of the rifle without resorting to melting it.

    The background.

    Bore is squeaky clean with prominent lands - but frosty - have worked on getting it this clean since last July. Have shot approx 300 rounds of milsurp and 100 rounds of Privi/reloads through it (20-40 rounds usually per range session) with thorough cleaning using Hoppes then carb cleaner immediately after each session. I have slugged the barrel at 0.3125/0.302 and the drag when pushing the slug through the barrel seems quite steady all the way down to the chamber. I have re-crowned the barrel at 11° using Brownells crowning tools. This rifle has a scout scope on it and an adjustable (modified) trigger. Will shoot about 2-3 MOA with best Milsurp I have found and has shot as low as 1.3 MOA during development of reloads so far.

    So why am I trying to do this - simply to learn how to do something interesting, and see how far I can take this old Mosin towards accuracy/precision. Yes I am aware of the OAL guages that could possibly give me the bullet seating depth info I want - but I didn't see anything listed for the 7.62x54R cartridge in the Sinclair catalog.

    Before making the chamber cast I pushed a lightly oiled patch completely through the bore with my brass jag. I then chambered a dummy round and then wadded the patch into the muzzle and pushed it back down the barrel onto the front of the dummy round and packed it there with the brass jag. I then removed the dummy round.

    I heated the Cerrosafe in a cleaned vegetable (food) tin can (with pouring spout bent into the can with needlenose pliers) on the kitchen stove until it melted. I then poured enough Cerrosafe down a piece of copper tubing (that sits in the action above the chamber) so that the cartridge area was about 1/2 filled. It appeared to solidify almost immediately. I let the Cerrosafe stand the 30 minutes to let it shrink, and then I tried to tap it out using the jag on my cleaning rod down the muzzle and my hand (at first). No way would this Cerrosafe come out of my chamber. I ruined a $25 Tipton cleaning rod and the jag trying to beat it out various ways (finally with a hammer). In the end I disassembled the rifle and heated the barrel with a propane torch to melt the Cerrosafe and got it out this way. I cleaned the rifle thoroughly (bought new Tipton cleaning rod and jag to clean with) and tried the process two more times - same exact results - can't get the cast out of the chamber - even when beating with a hammer.

    I was a little leery that I might have damaged the rifle while beating on the chamber cast with the jag/rod, but I took it to the range today (at 18°F - brrrrrr) and it shot well - just like it usually does - maybe even better.

    Anyone have any idea why I can't get this Cerrosafe cast out of my rifle chamber? Am I doing something wrong? Any suggetions?


    Last edited by LMyer; 12-18-2010 at 08:19 PM.

  2. #2
    Join Date
    Aug 2009


    I never tried it with Cerrosafe, but when I was a small boy casting lead soldiers, we smoked the molds with a kerosene lamp. I tnink cerrosafe is capable of forming a metal (solderlike) bond with steel, but some hard wax in the chamber should work at the temperature you are using

  3. #3
    Join Date
    Apr 2009
    North Central WV



    I had difficulties with my first one also.

    Here is what I did the second time around: Please keep in mind that I did a 6.5 carcano, and my bore slugged @ .270. I went to the hardware store and bought a 1/4" brass rod (.250) of sufficient length. Got the rod home and cut a 3/4" "slug" from one end with my dremel. I wrapped this "slug" with about 1 & 1/2 laps of masking tape, and it was tight to the bore. I pushed this slug down from the muzzle until it was in the rifling just above the throat. That was my "dam". Then I lubed the chamber/throat target area with white lithium grease. I then melted and poured and waited just a couple of minutes. Then I inserted the brass rod down against my brass "slug, and gave about three taps with a small hammer, and out she came.

    I believe the brass "slug" gave me a solid surface area against my cerrosafe. In other words, better than wadded up patching.

    Now, you are working with a .302 bore, so obviously another wrap or two of masking would be needed, and I hope the masking wouldnt slip on you. Anyway, that solid brass surface against my cerrosafe is what gave it enough solid surface area to work .. At least it did in my .270 bore.

    Good luck, BFB

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  5. #4
    Join Date
    Dec 1969
    Oldsmar, FL (Tampa Bay)


    Follow the Cerrosafe directions exactly. I did and had no problems. You don't need a fancy plug, just a wad of clean cloth inserted just before the rifling starts will do since it never gets even to the boiling point of water. You should clean, and not lubricate, the chamber and throat. Push the cast out within 30 minutes after pouring, the time it hits its minimum dimensions. For me it always taps right out, doesn't stick unless you try for a rifling cast. Be sure to warm up the rifle first, to stop it solidifying too soon and to get a complete cast. I used an old tin funnel with a copper tube stuck on the end for pouring.


    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 well known by all toolmakers and they will take it into consideration when making dies or reamers or gauges from your cast - if you will tell them the cast is of Cerrosafe. Cerrosafe melts between 158° - 190° F. It 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. The solidified casting should be removed from the chamber before, or when, it cools to room temperature. If allowed to remain in the mold over an hour, it will grip the chamber walls and be difficult to remove. Clean the chamber of the rifle thoroughly, then plug the bore immediately ahead of the throat with a small rag - but not so tightly it cannot be driven out. If possible, pour the molten Cerrosafe through a small tube into the bottom of the cast, gradually removing the tube as the chamber fills. If the barrel is cold, warm it to room temperature or above before making the cast. When cooled, remove from chamber, using a rod or dowel from the muzzle end of the gun.

    BTW if you just want a max LOA, then put the bullet in a sized case without crimping at what you think is the max loa, use a magic marker to mark the bullet/case mouth intersection, and load it. On ejection check for rifling marks on the bullet and the distance its pushed into the case, or sucked out a little if it sticks. If you fool around with, different lengths, maybe a little crimp if its not marking properly, you'll get the LOA for the bullet just touching the rifling.

    Also make sure case length is within the max limits to prevent overcrimping when the bolt cams closed. You can get dangerous overpressures from that.
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