Creosafe Chamber cast question.

[A pause for the COZ]

I have an ingot of this coming. Pretty sure I can figure out the casting part.
Not sure I under stand the measuring part. I assume it shrinks as it cools.
So do I need to add some to the measurements. Or is it close enough that its not a big deal?
I want to get after the pesky 2 groove 303 brit I have.

[blaser.306]

I beleive that it shrinks as soon as it cools but then " biggens up" to actual dimention within 12- 24 hours and continues to grow for a while after that? Others with more knowledge on the subject will chime in soon I am sure.

[Flyman]

Shrinks for removal, then becomes chamber size one hour after being poured.

[geargnasher]

Shrinks for removal, then becomes chamber size one hour after being poured.

Welcome to the forum, Flyman!

You are correct. After one hour, the rate of change is reasonably predictable for some time, and there is data available on the necessary correction factors.

Gear

[John Boy]

I assume it shrinks as it cools.
So do I need to add some to the measurements.

Contraction expansion factor versus time, measured in inch per inch compared to cold mold dimensions. Test Bar x 10
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"

[willvabch]

Any hints or tricks?

[Larry Gibson]

Any hints or tricks?

Clean chamber, cast chamber, remove cast, measure at 1 hour. That's what I do.

Larry Gibson

[john hayslip]

Yeah, run you blocking patch down the way you intend to remove the cast - FROM THE MUZZLE. A couple of times I have forgotten and started it in from the chamber and couldn't get the cast out without melting it out and starting over.

[JeffinNZ]

I just use sulphur with a splash of graphite.

[Alstep]

First time I tried a chamber cast, I waited a couple of minutes and then tried to punch it out. NO WAY!! Had to heat the chamber area of the gun to melt it out. As soon as you pour the cerosafe and it turns solid, punch it out, FAST! Don't wait. Also, preheat the chamber area with a heat gun, otherwise the casting will not fill out. Good luck.

[CGT80]

I did a chamber cast of my 40 S&W barrel last week. I used rotometals chamber material.....same chart as above. I cleaned the barrel and then lightly oiled it. The cast didn't seem to grow like the sheet indicated. My reading at 1 hour and multiple days later is the same. I ended up with a measurement of 0.403" in an XD 4" stock barrel with tens of thousands of rounds through it.

I am working with some boolit samples from an NOE 160 RN mold. I have some sized to .4015
and .4025. They are made of range scrap. It looks like the brass is swaging the soft lead. My dillon powder die is 0.397 and my rcbs flare dies are .396 and .397. I am only using as much crimp as is necessary to get the brass to chamber in this barrel. The barrel is a bit tighter than my dillon case gauge. Brass will go in the case gauge with some flare left on it, but it hangs up on the chamber. The back of the brass will go in the chamber. My commercial lead bullets are 401 but very hard. They don't swage down. I don't really want to run harder alloy. I do get some minor leading with the factory bullets.

I'm a little off topic, but I needed to type this out. I am open to suggestions with figuring out my actual needed boolit size. I may post this in a different section or under my own thread when I figure out where to put it.


I originally used the chamber material to cast my 30-30 and get a separated case out of the chamber. It was the only thing that worked, and it was very easy to do. The oil was suggested to keep the metal from sticking in parts of the action. I used foil to cover as much of the action as possible. Maybe I shouldn't have used oil when casting to get an accurate chamber size in the XD.

[KAF]

http://www.brownells.com/aspx/learn/learndetail.aspx?lid=10387