I need to buy some cerrosafe to make a chamber cast. I've never done one before, and am looking for any hints or advice those experienced in the process might offer?
Thanks!

I tried using cerrosafe for the first time last year. It is rather easy to use. I cut a coke can in half and bent part of the can to make a spout. I then placed the cerrosafe in the can and stuck it on the stove in a pot of water that was about an inch deep. I waited for the cerrosafe to melt. After I had plugged the barrel just ahead of the throat, I put on some leather gloves and picked up the soda can and gently poured the cerrosafe into the chamber. After a minute or two, I popped the cast out of the chamber with a cleaning rod.

Hope you find this useful:
The process of casting involves making a reproduction of the chamber/leade/bore by filling a portion of the bore and chamber with a casting material. There are a number of materials that can be used to make a cast. The most user-friendly is a material called Cerosafe. This is a metal alloy with a very low melting point at 158°F to 190°F (70°C to 88°C).

The manufacturer, Cero Metal Products, claims an expansion rate (after casting) in thousandths of an inch, per inch, as follows: 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. It must be noted however that the manufacturer is in the business of providing different alloys for different purposes. It may be worthwhile to acquire their literature and specs for study.

To make a ‘cast’ of a chamber/bore, a plug is inserted approximately an inch or so past the chamber, into the bore and Cerosafe is melted and poured in. A funnel can be made from a piece of three-eights copper pipe bent to fit and with the outer end flared to form a funnel. Also needed is a clean ladle. Heat the Cerosafe and, using a hair dryer, heat the vertically clamped action. While doing so, also heat the funnel and ladle. The extractor cut should be filled with release agent to prevent the cast from binding when set. Pour the cast. Remove all heat sources, wait about five minutes and then drive the plug and cast out of the bore by inserting a wooden dowel or a brass rod from the muzzle of the bore and tapping it through with care. The reason for waiting only five minutes is that Cerosafe solidifies and then expands as it cools, so the cast needs to be removed before it has a chance to expand and bind. The measurements of the cast should be taken as close as possible to one hour after the cast was poured, (which, according to the manufacturer, is when the new cast reaches its ‘true cast’ point) as the cast will change dimensions slightly as it ages.

With Cerrosafe, if measured exactly one hour after making the cast, the dimensions will be right on. If measured before that, dimensions will be slightly smaller than true chamber measurements. If measured after an hour, they will be slightly larger than actual chamber size. If you have the formula, you can calculate ‘actual’ size at anytime after an hour has passed.


A few thoughts on using Cerrosafe:

1. The tendency the first time is to melt a lot more than you will need. A tablespoon full is plenty unless you are after a full-length chamber cast. It is very easy to overfill and end up with some in the locking lug recesses, locking the casting into the chamber so do not do a full-length cast unless you really need it. For most ‘accuracy tuning’ purposes, knowing the measurements of the shoulder diameter, neck diameter and length, will provide plenty of information and all of that can be determined using only a tablespoon full or two.

2. You can use an old metal funnel, put the Cerrosafe in it, hold it in the chamber and heat it with a propane torch or use a hot air gun to get the metal into the chamber. If you do end up with a casting locked in a chamber, it is easy to remove, just heat the barrelled action with a heat gun set on ‘low’ and it will flow right out.

3. Working with Cerosafe is a lot easier if you remove the barrelled action from the stock before commencing.

4. Be sure to get the casting out as soon as it is solid, which is about 30 seconds after pouring, unless one has heated the whole barrelled action up above 165°F or so. Otherwise, if for some reason you are interrupted and you forget to remove it within an hour of the actual pour, it will expand to the point where you may have to melt it out and start over.

5. Save the printed formula that comes with the Cerrosafe so you can calculate true dimensions after the cast is more than one hour old.

SULPHER CHAMBER CAST

Another casting material is a mix of two-thirds sulphur to one-third micro graphite (approximate, anywhere in the 10 to 35 percent range is adequate). Sulphur requires a much higher melting temperature than Cerosafe but it has the advantage of neither growing nor shrinking once the cast has set. It is certainly possible to make a cast using sulphur alone but the addition of some graphite makes for a better, more easily removed cast.

A 4-lb. sack of sulphur can be had cheaply at the garden centre. Clean and degrease the chamber, put a paper plug about 1/2" into the rifling, drop a piece of COTTON string into the chamber, do not use synthetics, have a wood dowel longer than the barrel and of smaller diameter on hand. Place some sulphur in a small pan with a pour spout, using, preferably an electric hot plate, slowly heat the sulphur until it melts, do not let it catch fire, the smoke is poisonous. Pour enough liquid sulphur in to just fill the chamber, wait until the sulphur is completely hard, this depends on how large the chamber is, which governs the mass amount of sulphur that has to cool down. Carefully push on the cast with the dowel while firmly pulling on the string; it should come out easily once it starts to move.

Unlike Cerrosafe, the dimensions of the chamber cast do not change minute-by-minute and hour-by-hour, so how soon you measure the cast is not important. Sulphur is one of the few elements that do not change dimensions when going from a liquid to a solid state. Casts made with sulphur do not change shape dimensions even after many years. Sulphur can also be used to set machinery anchor bolts in concrete.

While sulphur alone can be used to make a cast, as described above, if you mix in a small amount of graphite it releases very easily after it cools. The best ratio, is somewhere between 10% to 33% graphite. Use a piece of poly tube through the receiver, pressed firmly against the rear of the chamber to keep from spilling it all over. Stick a funnel in it and pour until you see it in the tube. All you need is a couple of spoons full of sulphur, a little graphite, and a little heat.

All good info to note. Here is a big tip; make your cast with the barrel off the action. It can be a PITA to try and pour the material into the chamber while the barrel is still on.

quote:

Originally posted by Jim Kobe:
All good info to note. Here is a big tip; make your cast with the barrel off the action. It can be a PITA to try and pour the material into the chamber while the barrel is still on.

If you can't get take the barrel off for one reason or another, the other option is to use a funnel tube. I used a piece of copper tube through the action that fit the back of the barrel. The other option would be to put a bend in the tube and bring it out the action port. This helps to keep from spilling into the lugs and such, but does limit visibility a bit.
Greg

I stand the barreled action just slightly off plumb in my vise, ejection port up, and pour the stuff through the ejection port. At first it's like hitting the toilet at 3:00 am. You gotta be careful no to spill it all over the floor. With practice you can do it in your sleep.

If you use some type of funnel, it has to be kept as hot as the cerrosafe to keep it from stacking like coins in the chamber.

This is about 35 years old. It was made from a Tuna can. Grab it with pliers, heat it and pour directly into the chamber.

quote:

It is very easy to overfill and end up with some in the locking lug recesses, locking the casting into the chamber so do not do a full-length cast unless you really need it.

Since I'm trying to determine the caliber of a specific rifle, I'm assuming that I do indeed NEED the full length?
How big a problem in it if I do end up getting in the lugs?

Get into a position where you can see what you are doing and you should be fine. Provided your reflexes are good. Good news! Cerrosafe melts at a low temperature so if you screw up you can easily undo it with a little heat from a "propane" torch. Just make sure it has a safe place to run as you heat it.

Pouring a cast to determine caliber doesn't require the same precision that one would need when measuring dimensions. Go slow and you should be fine. If not, melt it out and start over.

Westpac, wold you care to make me one of those?

quote:

Originally posted by Jim Kobe:
Westpac, wold you care to make me one of those?

Sure, just send me a self addressed stamped envelope. A big one. But, isn't knowing how to bend a can one of the requirements for membership into the guild?

Actually the can bending is a function of the Tuna Can Benders Guild and I have not tried to join them, don't even know the requirements.

UA, 4/18/10

I have done about four chamber casts with cerro-safe (rifle and pistol) and have messed up about half of them, so maybe I can help you from making my mistakes.

First- great advice about not putting too much cerrosafe into the chamber. I overfilled my Remington 700 .270 Winchester chamber and had a bunch of solid Cerrosafe where it wasn't supposed to be. By tipping the barrel upwards and heating with a propane torch the extra ran out OK, leaving me with a usable chamber and throat cast.

When I did my first cast, on a pistol, I didn't heat up the pipe I was using to feed the Cerrosafe into the chamber and it solidified in the pipe. I also was quite careful in following directions while doing one chamber and as soon as it was cool enough I tried to remove the casting. No luck. waiting longer until it was cooler didn't help. I had to heat up the pistol barrel and drain the Cerrosafe out. Next time I coated the chamber with a thin coat of oil and it popped out easily.

It can actually be quite rewarding to do it correctly and then get info on your chamber or throat which is difficult to get any other way. After much swearing and with minimal skin burns I finally got what I wanted.

good luck- oldandslow