First, the length of the spring is only a small part of it. The number of coils and the wire diameter are much more important in determining the spring's strength and rate.
You need to determine what is causing the slide to be difficult to hand cycle by process of elimination.
Field strip it...
Sorry, but that defies Newton's 3rd Law of action and reaction.
There must be two interacting objects and two forces in an action-reaction system...a force forward and a force backward.
If the bullet exits before the slide moves, the action side of the system is missing. As far as the slide...
It will take a set and shorten after a couple hundred rounds...or less. Doesn't mean that it's worn out. The "set" is factored in. All springs will do it.
Just for giggles...
Does any body know why the Commander's "recoil" spring tends to run a little heavier than its 5-inch cousin?
Before we start...John Browning's original spring wasn't 16 pounds. It wasn't rated in pounds at all. It was specified as 32 and 3/4ths turns of .043 diameter...
The genius of John Browning.
The pistol in this demo is a Norinco.
The originals even had the grip screw slots sized to fit the case rim, and the bottoms of the slots were dished to match the rim's radius so that a cartridge could be used to remove them...
You're welcome. The narrator was me, and yes I have.
The AR15 firing pin's steps are matched to the hole diameters in the 1911 frame, making it a perfect armorer's tool.
Would you like to see my no-tool detail strip video?
I wouldn't worry overmuch about frame battering. The "recoil" spring's only real function is returning the slide. Whatever else it happens to do is incidental. The plain truth is that the slide doesn't hit the frame all that hard. As long as the slide strips and chambers the next round and...