This is how I was taught to change mags for the most part. I actually need to get out my new fancy gun belt and practice mag changes instead of sitting here on the internet.
I couldn't help but notice how easily they are racking the slides. They must have those things set up to run really light power loads.
8-10lb recoil spring is light.
Do they do this so they can shoot low power loads? Don't competitive shooters have to meet some kind of minimum velocity or power factor?
What other advantages are there to using light springs? Other than the ease of retracting the slide?
The weight of the recoil spring affects the way the gun recoils and more importantly how it recovers from recoil.
Most stock guns are over sprung from the factory because they don't know what kind of ammo the end user will be running. Some 9MM NATO stuff is hot and +p and +p+ stuff is warm.
A gun that is used in competition or shoots the same ammo all the time will benefit from tuning the weight of the recoil spring. Actually if someone is shooting say 9MM ammo of different brands then it will also help unless they are shooting wide swings like some really light 147 grain sub sonic and then shooting 115 +P+.
As far as what it does it is where the gun recovers to after it recoils. You want the gun to return to battery and the gun to be as close to point of aim for the first shot as possible. This depends on your grip and the gun and the ammo so what works for one might not work for another.
A example would be say a .45 1911 factory is usually 18 LB recoil spring. Most competition shooters are running 12-14 LB springs and I know some running 10 LBS. It depends on all the factors listed above.
It is sweet to be shooting fast and have the gun settle back in line as you are pulling the trigger for the second shot.
This is not just a competition thing as any serious shooter should do this with at least their carry gun. IMO
Loads at major competition have specific "power factors" that the declared ammo must meet. Minor (9mm for example, though some shoot .40 in minor) must be 125 power factory (velocity/bullet weight). Major is 165 (these are uspsa numbers. Idpa and Ipsc maybe different)
Loads at competitions that come from the chrono ammo the competitors brought have specific power factors. The one's on the belt..... maybe....