RECOIL SPRING STRENGTH

I am often asked how to determine the strength needed for the recoil spring. For an answer,
let's examine the operating theory of all dropping barrel locking actions like the 1911.

Starting with the moment the primer ignites the powder and pressure begins to build, the barrel is driven
forward against the upper lugs by the friction of the bullet in the rifling while the cartridge head is forced
back against the breech face.

The recoil spring holds the slide forward on the frame, and this keeps the barrel held up in the slide and locked
because its lower lugs are ramped up on the cross pin.

The explosive force of the burning powder and the propulsion of the bullet is thus contained safely while the bullet
is in transit through the barrel, and the recoil spring must be strong enough to keep the slide from retracting and
allowing the barrel to begin dropping.

If the barrel begins dropping too early because the ammunition load is not matched by the recoil spring strength
the grouping becomes a wild matter of chance and all possibility of real accuracy disappears.

The answer to the question becomes fairly simple. Since any spring strength that allows premature slide motion
will destroy accuracy, the recoil spring should be as strong as the gun can cycle with. If this proves more than
the shooter can handle, the use of less powerful ammunition is recommended. Any spring strength that allows
premature slide motion will not only destroy accuracy, it will eventually destroy the pistol.. Here's how.

One other thing becomes apparent. Before the shot is fired, the barrel is forced back against the upper lugs
by the recoil spring, putting whatever slack there is in the barrel and slide lug fitting ahead of the barrel lugs.
As the barrel is driven forward against the lugs, that slack is taken up smartly with a "slap".

If there is excessive lug clearance there will be enough inertial energy developed as momentum to severely
strain the lugs. Continual use of high powered loads can eventually crack the barrel lugs or slide lugs as
excess slack develops in the lugs due to wear.
Note, this has nothing to do with excessive headspace. That is another subject, with other problems.