How am I demonstrating a lack of understand of the locked breech? Or physics, for that matter? Please elaborate.
Since you asked...
lets start with this point,
Sure there is. Any load reduces velocity.
I was having a difficult time understanding why you felt the mainspring held the slide closed, until you said this. Your example of the car, taking longer under a heavier load is what a car does, but doesn't quite apply the same way to the slide of a pistol, in any practical manner.
The function of the mainspring is to power the hammer, and the force required by the slide to overcome the at rest tension of the spring, and then compress it is a constant, and something vastly overcompensated for by the energy of the slide during recoil.
I'm stating the dwell time as a function of time, not distance. The more effort it takes to cock the hammer against the mainspring, the longer the dwell time.
This is indeed a point of confusion. If I'm understanding you correctly, you are saying that without the resistance of cocking the hammer, the slide would move faster, and therefore, the mainspring "holds the slide closed" for a tiny amount of time.
OK, I get that. However, without covering the other things that ALSO "hold the slide closed" and by only looking at time as "dwell" and not time/distance, your statement implies that it is only the mainspring's resistance to compression that "holds the slide closed", which is, not the case.
Pardon the pun, but your explanation of the slide unlock sequence has a "missing LINK".
Yes, there is some resistance to rearward slide movement from the hammer at rest, the difference you can feel, simply cycling the slide with the hammer down, and again with the hammer cocked. It's not a lot of force, compared to the recoil energy of the slide.
IF you were to remove the mainspring's effect on "holding the slide closed", it would make NO DIFFERENCE AT ALL to the slide opening (unlocking from the barrel). The slide and barrel unlocking is a matter of DISTANCE, NOT spring resistance. When the barrel, running backward, locked with the slide, hits the end of the link's travel, the geometry of the angles of the parts yanks the rear of the barrel down, away from the slide, unlocking the two.
The point in TIME that this happens can be very slightly affected by changing the amount of spring tension needed to be overcome (and remember to include the resistance of the recoil spring, as it compresses and loads up), what you are calling "dwell", but the point in the movement of the slide and barrel that they unlock is always going to be the same.
Going to a heavier or lighter spring set is going to change the time by a tiny fraction of a second but does not, and cannot change the point of movement where unlocking occurs.
Another point, not clearly pointed out, is how springs "store" energy.
- The greater the amount of energy stored, the more force the recoil return spring will exert against the force of recoil. This means that the heavier the recoil return spring, the greater the feel of the recoil imparted to your hand.
yes, BUT, this only applies when comparing different springs, to each other, in their response to compression. Compress an 18lb spring with 300lbs force, and you have 18lbs potential energy stored. Compress a 25lb spring and you have 25lbs. ALL the excess is pass on as "felt" recoil. And the 300lb source doesn't notice the difference, either. The gun has many times the power to do either spring, so there is no practical difference, IF YOU STAY WITHIN DESIGN PARAMETERS.
Go far enough outside them, and things change. Go with a heavy enough spring and you don't need a locked breech. But you will need to accept other limitations.
7. The slide pauses momentarily at full rearward travel.
yes, because it hits the frame (recoil spring plug). How HARD it hits depends on different factors, but it does hit. Which is why the "shock buffer" pads some people use wear out and need to be replaced every so often. So, the slide is physically stopped from rearward movement, while the energy moving it is not, and continues reward, again, being felt as recoil. The "pause" is the time it takes for that energy to drop below the force stored in the recoil spring. When that happens, the spring moves the slide forward, again.
8. The slide begins forward under the stored power of the recoil return spring. Before the slide can get up much forward velocity, it is slowed again as it strips the next round from the magazine. This is very important.
9. Due to the engineered slowing of the slide, it comes forward to a soft stop.
- This is why it's OK to chamber a round from a magazine, but not to drop the slide on an empty chamber! A slide dropped on an empty chamber is not slowed and will batter the lugs and cause the sear to bounce. It strains the gun.
The "soft stop" you get when chambering a round is an additional reason to only load through the magazine, not the main reason, which is to avoid possible damage to the extractor. The 1911 extractor is, like the Mauser 98 extractor, not designed to snap over the rim of a chambered round. It is designed to have the rim fed up underneath it as the action closes. IN an EMERGENCY, they can be forced over the rim of a chambered round, but they might be damaged or completely break if this is done.
(modifications to the gun to allow the extractor to snap over the rim were not part of the original design, though they have become common since.)
As to the "hard stop" of letting the slide slam shut empty, this practice has been found to be detrimental to some highly tuned competition type guns. However, these guns all do vary from the GI specs, in several ways.
I've never found a GI spec 1911or A1 damaged due to any amount of letting the slide slam shut empty, and I used to inspect them for the Army. Simply put, the GI spec guns were built to take the abuse, and not fail, something a highly tuned customized gun usually isn't.
