I am in total agreement with that Hammergun. Let no one fool you, Any time a piece of steel passes through that "Critical" temperature with one being Sudden, there "IS" a possibility of warpage.
As I stated earlier with over 35 years in machine shops where I saw heat-treating done on a near daily basis, I do not recall Ever seeing a part come out with absolutely No Movement what-so-ever. This includes through hardening by air, oil or water quench depending upon the exact alloy, as well as Precipation hardening & some case hardening, though we did not do a lot of that.
With a new gun, the maker takes the risk that all will not go as planned, on an old gun the owner takes the risk, I simply choose not to take that risk on a gun of mine.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra