Chamber casting procedure

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Chamber casting procedure

Post by Kelsey Cooter » 12 Nov 2020, 11:49 am

Hey guys I've just bought an interesting old rolling block (haven't got it home yet) and we don't know if it is 43 Egyptian or spanish so I want to cast the chamber.

I've never cast a chamber before so I've been looking about on the net and it seems pretty simple with the alloy americans call cerrosafe.

Could you blokes run me through the steps you use to cast a chamber
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Re: Chamber casting procedure

Post by LawrenceA » 12 Nov 2020, 12:09 pm

Hi Kelsey
You will find that Cast Bullet Engineering also sell an equivalent to cerrosafe.

It has been decades since I did a cast so my memory may not be spot on. I am sure YouTube will have 50 versions of how to.
If I recall the woodwork was removed.
The barrel plugged with paper in front of the throat and the molten material poured into the chamber.
As the material changes dimension as it cools you need to remove the cast reasonably quick (it initially shrinks) and then once it cools (re expands) take your measurements. Removal of the cast was done with a steel cleaning rod. Tap, turn, tap, turn until the cast released.

Hope that helps.
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Re: Chamber casting procedure

Post by bladeracer » 12 Nov 2020, 2:33 pm

Kelsey Cooter wrote:Hey guys I've just bought an interesting old rolling block (haven't got it home yet) and we don't know if it is 43 Egyptian or spanish so I want to cast the chamber.

I've never cast a chamber before so I've been looking about on the net and it seems pretty simple with the alloy americans call cerrosafe.

Could you blokes run me through the steps you use to cast a chamber


Northern Smelters do a casting alloy like Cerrosafe.
I push a patch down just ahead of the throat.
I make a tube out of paper and drop it into the bolt lug recess to stop the alloy flowing into there. The plastic/cardboard tubes from NGK spark plugs are perfect for this. If it's a particularly difficult action to access you might want to make a "funnel" out of paper to direct the alloy down into the chamber.
I melt some alloy using a gas torch in a 95gm John West salmon can, with a small spout bent into one edge.
Using long-nose pliers I pour the alloy into the chamber.
Let it cool down (it shouldn't be really hot but is too hot to hold comfortably, it melts around 60C), then push it out with a cleaning rod. If it won't move without forcing it you may have gotten some into the bolt-lug recess, or too far down into the rifling. In that case, pull the action out of the stock and heat the barrel with the torch and the alloy will simply melt and pour out so you can try again. I have one rifle that the chamber is so badly pitted I haven't been able to do a cast at all, it simply will not release from the chamber walls. I'm going to have to do that one in short sections I think.
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Re: Chamber casting procedure

Post by bladeracer » 12 Nov 2020, 2:44 pm

Although the alloy melts at very low temperatures it is still quite a hard metal, significantly harder than a hardcast bullet.
It is particularly useful when trying to turn an awkwardly-shaped object in a lathe, place the object in a can of melted casting alloy so it sets around it, then you can chuck it around the cast, and melt it off when you're finished machining it.
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Re: Chamber casting procedure

Post by LawrenceA » 12 Nov 2020, 3:48 pm

bladeracer wrote:Although the alloy melts at very low temperatures it is still quite a hard metal, significantly harder than a hardcast bullet.
It is particularly useful when trying to turn an awkwardly-shaped object in a lathe, place the object in a can of melted casting alloy so it sets around it, then you can chuck it around the cast, and melt it off when you're finished machining it.

What an excellent idea!
One well placed shot is all it takes.
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Re: Chamber casting procedure

Post by Kelsey Cooter » 15 Nov 2020, 8:40 am

Thanks guys, I see northern smelters sells 500gram sticks so will order one and give it a go
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