But- the frame does get beaten by the barrel on recoil.
Not much. The slide hits it pretty hard, though.
I'll relate a little experience that I had with cast slides.
About 10 years ago, my ex-stepson approached me about building a pistol. He was short on cash, so he opted for an Essex slide and frame for a base, even though I warned him about the cast slide.
He's also a bullet caster and reloader, so he shot the gun hard as was his reason for building it...to get practice while preserving his pristine mid-60s production Colt.
At roughly 10,000 rounds, he busted the first slide where they normally let go...in the left corner just forward of and adjacent to the breechface...up to and through the port. (This particular failure is due to recoil stresses rather than impact with the frame.)
It went back to Essex, where they cherry-picked another one with the same specs. It came back with a warning to refrain from shooting handloads...along with the notification that they wouldn't warranty another one...but his load of choice was perfectly safe, and well below +P levels. He's been using the same one for years. (4 grains Bullseye with a 200-grain lead SWC)
The second slide let go in the same place, at approximately the same round count. He was convinced, and shopped the gun shows until he found a good Series 80 Colt top end assembly. With a few minor adjustments, the gun was back up and running. He's since logged about 30,000 rounds on the gun without further problems. The frame is still good to go.