Cerro-safe Chamber Cast

[BudRow]

Could someone give me a primer course on chamber casting with cerro-safe? I bought some years ago and fooled with it a little. I don't think I got it hot enough in a boiling water bath to flow very good. I plan to heat a small amount in a "Shot Glass" sized ceramic lab crusible over an industrial heat gun. I have an accurate thermometer and need to know the best temperature range for a chamber cast. I only want to cast from where the rifling starts back to just behind the case shoulder. Also should I remove the action from the stock and preheat the chamber area with a hair dryer? Would a little funnel fasioned out of cardboard work OK? I believe I read that you should wait an hour after it cools to make the measurements. How do you guys do it?
Best Wishes, Bud

[sundog]

Sulphur. And graphite. I have a bar of cerosafe for years, and never used it. Sulphur and graphite work real good. About 75/25, heat to a liquid and pour it in. Don't forget to plug the bbl in front of the chamber. A lightly oiled patched swabbed around in the chamber helps - just not too much oil. Not need to remove the action, but you may need to rig a tube or funnel to get it in there. I haven't neede to do one one for awhile, but my boss came in theis morning and told me he did one last night. Worked like a champ. Casting comes out real easy, too. Run a rod down the bore after about 15-20 minutes and give it a light tap. Out comes the casting. btw, be careful, as it's flammable.

[DLCTEX]

Aluminum foil works better to form a funnel IMHO. Dale

[KCSO]

Cerrosafe

I set mine on a ceramic plate on the wood stove (190 degrees) and heat untill it is all liquid. Prior to casting I lightly oil the chamber of the gun and plug the bore with an oily patch. Then I heat the action of the gun to about 100 degrees or so with a hair dryer. When the action is warm to hot I pour the cerrosafe in and let it harden. When hard tap out with a ram rod and measure in 1 Hour.

That said I try NOT to use Cerrosafe. I prefer to use sulphur as I like to keep my casting in a drawer with the rifle data. Cerrosafe is too darn expensive to keep and it isn't any cheaper using Bismuth shot.

[Larry Gibson]

Could someone give me a primer course on chamber casting with cerro-safe? I bought some years ago and fooled with it a little. I don't think I got it hot enough in a boiling water bath to flow very good. I plan to heat a small amount in a "Shot Glass" sized ceramic lab crusible over an industrial heat gun. I have an accurate thermometer and need to know the best temperature range for a chamber cast. I only want to cast from where the rifling starts back to just behind the case shoulder. Also should I remove the action from the stock and preheat the chamber area with a hair dryer? Would a little funnel fasioned out of cardboard work OK? I believe I read that you should wait an hour after it cools to make the measurements. How do you guys do it?
Best Wishes, Bud

WOW!!! What have I been doing wrong for 38 years? I clean the chamber. Then I put a clean patch over an appropriate jag on a cleaning rod and push it in from the muzzle until the patch end is just short of the throat area with maybe 1/2" of the lands to be cast also. I then put the rifle muzzle down in the bench vise to hold it. I have a small stailess steel cup used to poach eges with that I pinched a spout into the side of the lip. I hold this cup with a pair of pliers and put a suitable amount of cerrosafe (a previous cast no longer needed works fine) into the cup. I simply hold this over the flame of a propane torch until the cerrosafe is melted, usual in a few seconds. I then pour the cerrosafe into the chamber until it fills 3/4 or so of the chamber. The cast will cool in 2-3 minutes and a simple tap on the end of the cleaning rod punches it out. Make sure you catch it and support it as the casting comes out of the chamber to keep it from being damaged.

That's it, takes longer to explain than it does to do.

Larry Gibson

[mozark]

It helps to warm the chamber with a heat gun or hair dryer. Lay the rifle on a table, slide a 16" to 18" length of 1/2" copper tube through the action against the chamber, and direct the warm air through the tube. Warm is fine, no need to get things hot.

Overheating the cerrosafe will degrade it.

MM

[44man]

I've been fooling with that stuff for years and I have never gotten an accurate measurement with it. It has always been larger then actual bore size after the hour wait. It is more useful for checking chamber alignment then size. I think an expanded lead slug is better for checking sizes.
I have used it in a cold barrel and a hot barrel. If the barrel expands from heat the reading is larger too.
Barrels grow a lot with heat. I have had Dan Wesson's here that the barrel nut was so tight it could not be unscrewed. I would take a hose and funnel and pour boiling water through the barrel. I could then unscrew the nut with my fingers.

[Larry Gibson]

hmmmm...seems cerrosafe has it's detractors. All I can say is I've been using (over and over again) the same two ingots I got from Brownell's 37 years ago. There is very little heat when it is poured into a cold barrel to cause much expansion. Then if there is any expansion of the barrel from the heat of the melted cerrosafe I'm sure the strength of the contracting steel will compress the quite soft cerrosafe when it cools. At any rate I get quite accurate measurements with it. It is also great stuff to remove a seperated case from a chamber with when other methods fail. Simply follow my instructions in my 1st post and when the cast is easily punched out of the chamber the seperated case comes with it. My directions are the original instructions for it's use BTW that came from Brownell's. Perhaps I've been successfull using cerrosafe because I followed the instructions and did not "fool around" with it. It works for me.

Larry Gibson

[44man]

Larry, thats the way I use it, in a cold barrel. But for example, my Browning BPCR is supposed to have a .458 barrel according to Browning. Cerrosafe shows .4608" after one hour. An expanded pure lead slug shows .4592". The instructions state to wait one hour and the casting will expand to the exact bore size. I start measuring right away and every 15 minutes up to 2 hours and still do not get a usable figure. Close enough for a grenade, maybe.
The best way to measure a throat is to take a fired case, put a brass rod into it to hold a pure lead boolit to touch the rifling, chamber it and put a brass rod down the bore to beat the boolit out to the throat diameter.
You can follow instructions until you are blue in the face but if the material does not plan on doing it and can't read, what do you do? Does the ambient temperature in your shop have to be 70.003478 degrees to get the proper expansion?

[montana_charlie]

I've been reading along without comment because I haven't gotten serious about a chamber cast...even though I do have some Cerro-Safe.
Yeah...I made a chamber cast back when I first got my rifle, but it came out kinda wrinkled...so I decided to wait until I really needed one.

But, the first thing I did with it was to cast a bullet.
You see, I lucked into the sale of an NEI mould which looked like it would be great for a Sharps (if I happened to find one), and I grabbed it.
So, there I was with a nice mould...but no handles for it...and a hankerin' to see a bullet from it...and I had this Cerro-Safe stuff.

Didn't take long, holding the blocks in my hand and heating a little cupful on the stove, to produce a little jewel to admire. Cutting the sprue was a bit tough, but it came off clean.

Later, I loaded that slug into a damaged case to make a dummy round for adjusting dies...and eventually pulled it apart, when I moved on to a different bullet design.

Then comes this discussion. Yeah, I read the instructions...and I'm aware this stuff changes size with age. But you guys made me curious.

That original bullet is laying in the melting cup, waiting to be remelted, so I just measured it. Now, I know for a fact the mould throws .460" bullets when using 30 to 1 alloy. This Cerro-Safe bullet (roughly a year old) measures .459".

Comments?
CM

[44man]

From what I understand, it tends to shrink again after a long time. I am not totally sure but it is some strange metal. Nothing is sure except death and taxes.

[OLPDon]

Sulphur. And graphite. I have a bar of cerosafe for years, and never used it. Sulphur and graphite work real good. About 75/25, heat to a liquid and pour it in. Don't forget to plug the bbl in front of the chamber. A lightly oiled patched swabbed around in the chamber helps - just not too much oil. Not need to remove the action, but you may need to rig a tube or funnel to get it in there. I haven't neede to do one one for awhile, but my boss came in theis morning and told me he did one last night. Worked like a champ. Casting comes out real easy, too. Run a rod down the bore after about 15-20 minutes and give it a light tap. Out comes the casting. btw, be careful, as it's flammable.


Sundog:
I have not yet done a chamber cast and it one of those when I get aroundtoit. I have a bar of what appears to be graphite looks just like a 1 1/2 x 1/2 x 6 no.2 lead pencil without the wood.
Let me cut to the chase how do I make your Sulphur & Graphite mixture and were would the best place to get the ingredance's.
Thanks for your input.
Don

[leftiye]

That's- A round tooit. No square, oval, flat etc. tooits allowed!

[Larry Gibson]

Larry, thats the way I use it, in a cold barrel. But for example, my Browning BPCR is supposed to have a .458 barrel according to Browning. Cerrosafe shows .4608" after one hour. An expanded pure lead slug shows .4592". The instructions state to wait one hour and the casting will expand to the exact bore size. I start measuring right away and every 15 minutes up to 2 hours and still do not get a usable figure. Close enough for a grenade, maybe.
The best way to measure a throat is to take a fired case, put a brass rod into it to hold a pure lead boolit to touch the rifling, chamber it and put a brass rod down the bore to beat the boolit out to the throat diameter.
You can follow instructions until you are blue in the face but if the material does not plan on doing it and can't read, what do you do? Does the ambient temperature in your shop have to be 70.003478 degrees to get the proper expansion?

I'm not sure what you mean by "a useable figure". All manufactures have +/- tolerances. Are you expecting it to be .458 exactly because that is what Browning's brochure says? Or are you expecting it to be what the lead slug says it is? How are you sure the lead slug is correct and the cerrosafe casting isn't? If you read my first post you will see I don't agree with the "ambient temperature in your shop have to be 70.003478 degrees to get the proper expansion?" concept plus the other fastideous measures suggested. Again, I get quite consistant measurements from cerrosafe castings.

Larry Gibson

[BudRow]

Well last night I used the cerro-safe and made a successful chamber cast. It had minimal wrinkles and bubbles and was easily measurable after an hour. However tonight I tried Sundog's sulphur & graphite method and found it to be much better! The casting has a hard plastic like texure with no flaws - I feel this is the way to go. I assume it is dimensionally stable over time so I guess you can measure it as soon as it reaches room temp and be confident it is accurate. My cerro-safe will now become just a curiosity on my bench Thank You Sundog!
Best Wishes, Bud

[Larry Gibson]

Montana

Come on, you've been around long enough to know that "Later, I loaded that slug into a damaged case to make a dummy round for adjusting dies...and eventually pulled it apart" will compress and alter the diameter of the bullet, especially when it is pulled. You also don't say what the diameter was befor you loaded it, only that it is now .459 after that. What was it before?

BTW; the wrinkled chamber was probably from and oiled chamber. To get a good cast the chamber must be clean and oil free, just like a bullet mould.

Larry Gibson.

[44man]

Larry, I knew Browning was wrong and I had a larger bore. I talked to them and they said it SHOULD be .458. If I drove a .458 boolit through the bore it would not touch the bottom of the grooves except where it was upset.
I could not get a .457 or .458 boolit to shoot at all so I must have made about 5 castings of the chamber and the start of the rifling. Every casting said .4608. It is a little smaller if measure right away. After an hour and even after several days, it is .4608.
I then lightly oiled the bore, put a slug just into the rifling and upset it with two brass rods. That measures .4592 every time.
So, which measurement do I really trust?
I will make a test tomorrow with my revolver. I know the exact size of the throats. I will make a casting of it and post back.

[Larry Gibson]

Larry, I knew Browning was wrong and I had a larger bore. I talked to them and they said it SHOULD be .458. If I drove a .458 boolit through the bore it would not touch the bottom of the grooves except where it was upset.
I could not get a .457 or .458 boolit to shoot at all so I must have made about 5 castings of the chamber and the start of the rifling. Every casting said .4608. It is a little smaller if measure right away. After an hour and even after several days, it is .4608.
I then lightly oiled the bore, put a slug just into the rifling and upset it with two brass rods. That measures .4592 every time.
So, which measurement do I really trust?
I will make a test tomorrow with my revolver. I know the exact size of the throats. I will make a casting of it and post back.

Quite frankly I would trust the cerrosafe. Obviously it was consistant for you as was the lead. However the cerrosafe has minimal shrinkage and it is a casting which means it flows into and fills out around the rifling. Seems to me that driving the lead slug from the thoat into the forcing cone would give false, though consistant, readings. Reason being is the throat is a forcing cone of sorts. As the lead is swaged down this cone there is a slight taper to it. Seems that unless there is some sort of anvil in the barrel for it to hit against and swage out into the rifling completely it is not giving a true reading of the groove depth. You mention two brass rods - is one used as an anvil in the barrel? If so then I really don't know.

What I do know is the cerrosafe has minimum shrinkage and can't come out larger than the bore. Neither can the lead. The lead can possibly not be swaged up completely. Since neither can come out larger than the bore I would believe the larger reading. If it were the lead that is what I would believe but it is not. As I said I've used cerrosafe for 37+ years and it's been a consistant performer Using the measurements obtained have proven correct also.

Larry Gibson