Originally Posted by
Bowdrie
The .45ACP is a very forgiving round to load, that is unless you're an upper competitor at the 50yd bullseye, then thousands of an inch of several dimensional measurements can start stacking up against you.
One thing that is generally agreed upon; You don't use the contacting of the bullet against the leade as a way to control headspace or to stop the round from going into the chamber further.
That's just a recipe for pressure spikes.
In a perfect world the slide will close with the hood-end of the barrel just kissing the breech face and only leave a very few thousands of length between the chamber shoulder and the breech face for the cartridge to "move back-and-forth, so to speak.
The cartridge wants to headspace on the chamber shoulder without trying to unduly pull the extractor forward.
In practice, given the tolerances of chamber and case lengths most 1911s are using the extractor to some degree to retard the forward movement of the cartridge.
When the breech closes the cartridge still has inertia and wants to continue moving forward, we want the case to contact the chamber shoulder without straining against the extractor too much.