Chamber Cast

J

johnm1

New member
I am having a little trouble casting a chamber. I have read the instructions at Brownells and watched a couple of videos of the process. It looked pretty simple but I had to re-melt the Cerro Safe both times this evening. I did locate the locking rings inside the Chamber and kept the casting material below that and I did coat the chamber and barrel with CLP. The instructions suggest (at least in one set of written instructions) that the cast be removed within minutes and no later than 30 minutes after casting. I did find one set of written instructions suggesting that the casting be removed at 30 minutes after casting. I my two attempts this evening I waited 5 and 10 minutes respectively but was unable to drive the casting material out.

Should I be waiting longer before trying to drive the casting material out?

As a novice, is there anything I am not considering?

If it makes a difference, I suspect the cartridge is 8x50R (rimmed). Confirmation of the cartridge is why I am making the cast.
 
I use paste wax to lube the chamber. Get a large patch good and gooey with paste wax, swirl it around in the chamber a bit, then drive it into the throat to plug the bore.

I heat the Cerrosafe in a steel can that is bent on one edge to form a spout, and pour the molten metal directly into the chamber. Depending on how large the chamber is, I drive the cast out after about 5 minutes, lead and lead alloys expand slightly as they crystallize.

You don't need a perfect cast, but it needs to be good enough to be able to get good measurements to identify the chambering.
 
Thanks Guncrank,

Maybe I should have done more research on the casting materials before I bought it. Everything I read (and we all know that if you read it on the internet it must be true) led me to the Cerro Safe.

Thanks again. I'll keep trying.
 
Cerro safe shrinks as it cools, then enlarges to be actual chamber dimension, then continues to enlarge.

The numbers are well known.

30 minutes sounds like the 'nominal' size time.
http://www.brownells.com/.aspx/pid=384/Product/CERROSAFE-reg-CHAMBER-CASTING-ALLOY
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.
Click to expand...

If you wait more than 30 minutes it is going to be a lot harder to remove.
Get it out before then so it is smaller.
 
Thanks all for the suggestions. I did manage to get a cast this morning. I had read the instructions and the tips at the Brownells website. One place suggested removing the cast immediately after it hardens and the other suggested to remove it closer to 30 minutes. Even though the instructions indicate that the cast area should be dry I succeeded while lubricating the chamber. CLP didn't work and I ended up using, of all things, Pam anti-stick spray that my wife suggested. Not sure if it was the lubrication or the size of the cast or jsut dumb luck that made it work, but I did end up with a cast that was good enough to verify the chambering and measure the throat erosion.

I immediately tried to cast the last 2 inches of the muzzle but could not remove the cast without remelting it. I'm sure it's operator error. I did forget to lubricate the muzzle. Not sure if it was the lack of lubrication or I tried to cast too much of the rifling. If the throat erosion is any indication, the muzzle wear will be 5 or 6 thousandths. The barrel dates from at least 1917. It could actually be either 1907 or 1897 but I doubt it goes back that far. I was in the possession of two different countries. Austria-Hungary and Czechoslovakia.
 
I immediately tried to cast the last 2 inches of the muzzle but could not remove the cast without remelting it.
Click to expand...

You have to unscrew it from the rifling, turn as you pull.

This is also required if a chamber cast extends very far into the rifling.

If any rifling is in the cast it cannot pull straight out.
 
You must log in or register to reply here.
Back
Top