[animal]

hmm ok, I normally think of receivers as screwed solid as bloody hell to the barrel. What you’re talking about is pinning or welding the assy if cost and mass production is a factor ?
dunno if you could expect much inherent accuracy unless you go to a lot of trouble with an interference fit.

I don’t understand why you would want the chamber to move as that would increase bolt travel and it moving relative to the barrel would (I think) create nightmare gas issues. Maybe I’m missing something.

The only gun I can think of at the moment … that isn’t itty bitty and moves the chamber … is the Model 1911 Winchester shotgun. In it, the chamber is stationary with respect to the barrel … the entire barrel assy moves back upon firing and then rebounds forward … leaving the bolt at the rear and uncovering the empty shell as it moves forward for ejection and feeding the next one. … a simple recoil action, roughly the same bolt travel … and the barrel isn’t moving forward until gas is expended. The force of the gas pushing the barrel back delays the ejection.
You might say it’s a gas-dampened recoil-operation. The need for a delay in the action comes when you want to pull the empty from the chamber after the barrel pressures subside (that the 1911 provides with the movable barrel). The delay mechanism is the connection to the force exerted by the gas.

Sorry if I’m being thick here, but I can’t picture what you’re trying to do. Good luck with it.