My featherlight, 1952 vintage, has a steel receiver.
Yea your right. It was the ultralight that had the aluminum. I was going by memory. That shotgun was made for so many years spanning at least 25 versions, so with M37s having different names like featherlight, featherweight, ultralight, ultra-light.... it is easy to mix them up without pulling out a book. There was even a waterfowl version. I still would not want to risk shooting any hotter than normal loads in it.
Speaking of Tungsten Matrix, I shot some heavy 12 and 20 GA Tungsten Matrix last year on Mountain Sharptail and Sage Grouse. They had some kick to them too. Ammo cost was not a big deal for that hunt considering I was hunting a bird with a possession limit of 2 that I may never be able to hunt again because it is about to go on the threatened or endangered list. But If I were a rich man and money was no object, that Kent Tungsten Matrix is all I would hunt with.
"Onward up many a frightening creek, though your arms may get sore and your sneakers may leak. Oh! The places you'll go!" ~ Dr. Seuss