Sort of odd that the steel barrel failed when it is the receiver that is made of pot metal.
I re-read this with a little chagrin. I have to admit that it seems an unfair assessment.
I would like to revise my opinion.
Henry does indeed use zinc-aluminum alloy for the action cover/upper receiver, and for the inner receiver as well. Something to consider is that the receiver cover is not simply a cosmetic overlay. It also is the upper stock tang.
The gun is easy to disassemble and reassemble, and uses large diameter steel pins for the steel lever to rotate on and for the spring-loaded locking block to pivot on.
The large surface area of the locking bolt pin better distributes the bolt thrust forces to the receiver. All of the pins are easy to remove and to reinstall without using force to drive them out.
And not all ZA alloys are cheap pot metal and brittle.
Lee valley tools for instance uses ZA-12 alloy to make a number of woodworking tools, and the lever caps on several of their VERITAS hand planes use this alloy.
ZA-12 is characterized by excellent tensile and compressive strength, but like all alloys like this it, I think that it lacks the ability to form female threads that are as strong as are grey or ductile cast iron, and certainly not as strong as hardened brass or most steels. LVT does warn in their instructions that you should not over-tighten the lever cap tensioning knobs, which have steel or brass threaded shanks that screw into the lever caps. I have found that the ZA-12 parts on the planes that I own are certainly adequate for a lifetime if not abused.
ZA-12 is 86.5% zinc, 11.5% aluminum, 1.2% copper, less than 1% of trace other metals, and has 40,000 PSI of tensile strength.
Henry rim-fire lever action rifles, however, use ZA-5 alloy, which is 95 % zinc, 3.9% aluminum, 1% copper, and .1% of trace other metals. It has 48,000 PSI tensile strength.
The copper adds strength but reduces ductility. ZA-5 has more tensile strength, but less impact resistance than the most common ZA alloy, ZA-3.
ZA-12 would probably be a better alloy to use because of the greater aluminum content, but is probably more expensive.
While all ZA or ZAMAK alloys might be called "pot metal", actual pot metal is very impure and brittle, because of low pressure die casting and contamination. It was never intended for anything but pretty much decorative and low-stress castings.
So, while a primarily aluminum alloy would be better, like A380, that Ruger uses for the Wrangler cylinder frame, I think that ZA-5 is a pretty good metal to build a low cost .22 rifle receiver out of, as long as that rifle is engineered with the alloy limitations taken into account.
And, as long as you are careful not to strip the threads when you tighten the screws.
Henry uses star lock washers on the action cover/upper receiver to facilitate this.