The 73 is kind of hard to work on a stuck/separated case as you can't get directly into the chamber end of the bbl.
But using a cleaning brush slightly over size for the inside dia of the stuck portion usually works well on these low pressure rounds.
Run it down from the muzzle and back out of the chamber. Then pull it slowly back toward the muzzle til the brush is inside the stuck case .
Then reverse, and push the rod and brush back out toward the breech.
The oversize bristles will resist turning direction inside the case, but will with some effort. Then they will be grabbing and pushing in the right direction to push the case out of the chamber.
The second method using cerosafe or any of the low-melt alloy metals works well.
Use as described above already.
Cerosafe is one of the Bismuth alloys used for casting at low temp , below 300F
There are several diff alloy make-ups and they have diff melt temps.
Bismuth, lead, tin, cadium,,maybe some other stuff
The lowest is a melt temp of 158F
The highest is 280F IIRC
The Cerosafe stuff is right around 200/203F
The stuff that melts at around 158F is commonly called Woods Metal
You can buy the different grades in bar form from places like MacMaster/Carr
1 lb of most grades cost around $35. Except the 281F melt stuff which is more expensive at around $60/lb. That was the last time I saw it for sale.
I don't know what Brownells sells theirs for now but it was never inexpensive.
elts in boiling water. I use a double boiler type set up. Thats an old sauce pan with the water in it and a cat food can with the Cerosafe in it placed in it.
Handy stuff for chamber casts and holding odd shaped parts for machining or even hand work.
Filling or backing a thin gun part while engraving is a common use. Place the whole thing in boiling water when done and the stuff just melts away into a blob in the bottom of the water pan.
Pour the Cerosafe into the plugged bbl and let it solidify. But don't wait more than about 20min to try and punch the plug back out.
The metal when first cast and is still hot is slightly (by a couple .000) smaller in dim than the chamber.
It will punch back out rather easily easily.
After it cools,,I think they advise a 30min max time, the metal expands back to 100% size of what ever it was cast in. Thats so engineering types can get a perfect or near perfect measurement of the inside of whatever they were casting.
But if using it to remove the stuck case or even a doing a chamber cast,, leaving the casting in place too long will make it nearly impossible to punch backout again as it is seized into place by expansion.
I can speak from experience!
Then you have to carefully heat the chamber area to 200+F to melt the stuff again and let it pour back out.
Don't spill it!
I've been using the same 3#'s of the stuff I bought more than 40 yrs ago.
Supposedly, if you over heat these alloys it will 'ruin them' in some way. I've read that many times. Maybe it separates the different metal alloy components and then they don't go back into the alloy mix again when cooling off. So you spoil the low temp melt quality of it.
Don't know, but it's too expensive to try and spoil it just to find out.