Yep, once the turret/tailstock hits a stop, the die holder slides out on its keyed shaft until the key disengages, then spins free.Probably on some sort of a "telescopic" fixture that would allow the die to follow along as it threads. That fixture would mount to the tailstock or a turret.
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Yep, once the turret/tailstock hits a stop, the die holder slides out on its keyed shaft until the key disengages, then spins free.
Those die holders could have been shop made, so you might not find an exact representation. But here is something similar, you can get the idea.