Yes and no. You can skip heat treatment buttttt if you do the rivets holding trunions will stretch and egg out the rivet holes at some point or crack the reciever then you have a loose trunion under recoil leading eventually to explosive disassembly.
While it will shoot for a good while untreated its just not a great longterm idea.
Its kinda like the polymer craze for ar15s skip some critical step or material for dubious benefit. Doesn't make sense to me.
"Gun control: The theory that a woman found dead in an alley, raped and strangled with her panty hose, is somehow morally superior to a woman explaining to police how her attacker got that fatal bullet wound." — L. Neil Smith
The problem with being stupid is you cannot simply decide to stop doing dumb things...
"I crapped my pants to avoid the draft!!" -Ted Nugent