DM - Chamber casting is quite easy. I would suggest that you only attempt a chamber cast with Cerrosafe. You can get this from Brownells - 515 623-5401. Half a pound is $10.27 and can be used over and over. I would avoid wax because of the clean up is a pain. Simply melt Cerrosafe on the stove and poor. As it cools, it releases from the chamber. You can then make all your measurements from the cast.
Z
Posts: 10780 | Location: Test Tube | Registered: 27 February 2001
By all means use cerrosafe and follow directions in package.
I find that removing the action from the stock and wrapping it with a heating pad on high for 30 minutes before casting gets best results. (You want the rifle to be about 105 degrees F.)
Don
[This message has been edited by Don G (edited 04-26-2001).]
Has anyone ever made a chamber cast using sulfur? I seem to remember that you could melt sulfur and get a dimensionally stable chamber casting, but I've never tried it.
Posts: 7799 | Location: Between 2 rivers, Middle USA | Registered: 19 August 2000
quote:Originally posted by MarkWhite: Has anyone ever made a chamber cast using sulfur? I seem to remember that you could melt sulfur and get a dimensionally stable chamber casting, but I've never tried it.
Yes, but cerrosafe is easier, and not as smelly if you screw up and ignite the sulphur by overheating it.
The object of making a chamber cast is to be able to measure it precisely and cheaply.
You can pour anything you want in the chamber, but only certain things will,
a) be easily removable, b) hold the internal dimension by shrinking from the "inside", c) be tough enough to handle and measure without damage, d) last long enough to become a record of work done.
Color crayons, concrete, epoxy, and ear wax might do one or two of those, but not all of them.
If all you want to do is measure neck diameter....yes.
But the cast allows you to measure taper with an optical comparator. You can see the quality of the polish or locate and inspect for damage or problems. The "chamber" is held in your hand. You can spin it on your concentricity guage to measure eccentricity or other problems. You can also inspect the throat for erosion and overall condition. You can measure ALL of the chamber with a forty dollar micrometer while it takes a $300 remote reading internal mic. to measure one spot........ And the barrel has to be pulled to do it.
To answer you question, NO. A cerrosafe case will give you a multitude of dimensions, can be set aside for future reference and is exceedingly accurate...
Whenever I build a new gun for competition, I make a Cerrosafe cast and keep it for reference. This way as JBELK has clearly stated, you have a absolute reference with respect to concentricity and finish. With future casts you can measure throat erosion and other problems. Cerrosafe casting is easy to do and very inexpensive. You get exact measurements and , thus you can see exactly what your chamber looks like. I tried to tell a guy on the Big Bore ssection that he should do a chamber cast on his 458 win mag to 458Lott conversion ( done by hand reaming) without removing the barrel to see what a classic egg shaped ( and probably ringed) chamber really looks like. This is what chamber casting is for- it doesn't lie!-Rob
Posts: 6314 | Location: Las Vegas,NV | Registered: 10 January 2001
I certanly wouldn't want to argue any of the positive points made regarding use of cerrosafe, but...
It ain't manna from heaven. One of cerrosafe's greatests values lies in its uniform SHORT-TERM shrinkage. It is supposed to shrink exactly 0.001" after an hour of cooling. Good to know for precision measurements. HOWEVER, the few nationally reknowned reamer manufacturers and tool-and-die makers I know, WON"T USE A CERROSAFE CAST FOR DIMENSIONS TO MAKE A REAMER! It shrinks and grows with too much variability over time. Talk to Dave Manson at Manson Presision Reamers. 810-953-0732.
If you want diameter or precise length MEASUREMENTS, use once-fired brass. If you want to INSPECT the chamber and throat and leade, make a cerrosafe cast.
I have used sulphur as well. I was satisfied with the results. However, get the cerrosafe, and use it for what it was designed - inspection and coarser length, (as opposed to diameter), measurements.