If we can rely on Tuner's 0.2" of travel before the lugs completely disengage, then we know the barrel starts tilting much sooner. Somewhere close to 1/10th an inch, maybe?
It's measurable.
The barrel drop begins almost immediately when you hand-cycle the gun because the geometry of the lower lug lets gravity pull it down as soon as the lug backs up on the slidestop pin.
It doesn't do that when the gun is fired.
(And here comes another 5-page argument, but here goes.)
The barrel engages vertically, but it locks horizontally with the barrel and slide lugs in opposition under high shearing forces...because the bullet exerts a forward drag on the barrel while the slide is pulling the barrel backward against that forward force.
This forward drag has been measured by the man who posted those pictures. It took 103 pounds of force to start the bullet into the rifling, and 93 pounds of steady force to get it to the muzzle.
This represents the strongest resistive/delaying force acting on the slide in the whole system. It explains why a locked breech pistol can be safely fired without a spring and it explains why the barrel can't unlock with a heavy-for-the-caliber bullet and high pressure can't cause the barrel to unlock early.
With the lugs locked horizontally in opposition under whatever pressure per square inch exists when the barrel starts to move backward...the barrel can't drop via gravity. It can't. Don't trust your observations while hand-cycling. It functions differently when the gun is fired.
The only analogy I can offer to demonstrate this is the a door.
Stand in front of a door that opens away from you and turn the knob. It turns easily.
Place your hand 2 feet above the knob and push with moderate force...and try to turn the knob. You'll notice that it's much more difficult, and...depending on a few factors...you may damage the mechanism if you force the knob to turn. The striker is forced against the striker plate...locked in opposition under shearing force and trying to get the striker to move is fruitless and possibly destructive. A 10 year-old child could stop you from opening that door.
So, even if a bullet and high pressures are present when the barrel reaches the linkdown point...which can't happen, even with a heavy bullet...
With the barrel lugs engaged horizontally under this shearing force at however many thousands of pounds psi exists when the link starts to pull...I strongly suspect that the link would fail before it disengaged them and allowed the breech to open, and the he lugs would almost certainly be damaged even if the link held and succeeded in pulling the barrel down.
The bullet drag/resistance/delay is something that few people stop to consider, or...even if they allude to it...insist that it's not a significant factor because of the high forces driving he system...but a hundred pounds of resistance is a hundred pounds of resistance no matter how you cut it. It trumps slide and barrel mass and all the resistance imposed by the springs combined.
And now, I gotta go get all these dogs out and prepare myself for the next wave of snark and condescension that these points will doubtless give rise to.
Regards