With the standard round, the base of the bullet is about a 10th inch forward of the muzzle when the slide has moved a 10th inch.
Sorry, wut? Can you please explain how you figured this out? And how this possibly applies to all handguns, universally?
I did some measurements on my Glock 27, which I have had the extraction problems on hot loads, and I found something very interesting.
Glock 27 slide + barrel weight = 413 grams.
180 gr bullet = 11.7 grams.
Distance of slide/barrel movement before the barrel lugs contact the locking block = approximately 50 mics* +- 2 mics, or 1/20th of an inch. (Measured with the depth stop on my calipers on the back of the slide).
According to this calculation (which I'm not a physicist it might be wrong) 0.050" x 413 grams/11.7 grams = 1.76". If you don't factor in the recoil spring, this would mean the bullet is still in the barrel by the time the barrel hits the locking block. Of course it takes a much longer distance than 0.05" before the breech opens any considerable distance, but I find this very curious in terms of potential to affect accuracy and extraction. (The hot loads I had extraction problems with were also all over the map, even factoring in the flinch factor, but they were top notch in my FNX). I think it's safe to say the 17-18 lb recoil spring is a rather significant factor in this specific gun and that it does more than just return the slide to battery.
The way the spring factors in is more complicated. A spring applies force over distance, but in this case we are also concerned with the duration in time. If you slowly pressed the slide of a gun back with a ton of force, the frame would also just move back. Even with a hand holding it, the frame would press farther back into the shooter's hand before it started moving in relation to the slide. But with a higher impulse, the frame would not move as much in that first fraction of an inch of travel. The inertia of the frame would start to factor in. Thus, the slide:frame movement would be greater in the all important first 1/10th of an inch. This is one of the reasons why I reckon that hotter loads could make this gun unlock too soon, even though the bullet weight is the same.
*Edit: sorry, made a mistake in measurements. Will update with an edit.
Distance before hitting the locking block is right on 90 mics. This changes the distance of bullet travel to 3.17", which is well out of the barrel. So now this muddies up my previous reasonings. The extraction problem could be exacerbated by the way the Glock extractor rod/spring is setup, causing some inertial inefficiencies, but I still want to think pressures can be too high and/or the brass still needs just a little time to shrink back for extraction in the moments after the bullet has left the barrel. As for inaccuracy of those hot loads, I don't know.
My FNX is harder to measure, because there's no good spot to put the calipers. But it appears to be around 150-190 mics depending on how I measure, and the weight of slide+barrel is 468 grams, with a similar weight spring. This gives it a much larger margin of error.