So, why does the Commander’s spring run a little heavier?
It’s simple physics.
A moving object is subject to outside forces fighting to decelerate it and bring it to a stop the instant that it starts moving. At least here on terra firma. The two main forces are friction and gravity. In the case of the forward moving slide that has to strip a fresh cartridge from the magazine…bounce it off the feed ramp and over the top of the barrel ramp…force the rim under the extractor…and go to battery…we’ll focus mainly on friction, even though the inertial mass of the cartridge itself plays a role.
In short, the slide relies on a certain level of momentum to assist the spring in returning the slide successfully to battery, and even though there’s not a lot of difference in mass between the two slides…everything means something. The shorter slide is demonstably lighter/lower in mass…and momentum is a function of Mass X Velocity.
The 5-inch 1911 is actually over-engineered in this respect. If all is to spec within the gun, it will run with a much lighter spring. But guns vary a little, and guns get dirty, and gun owners often neglect to place a drop of oil in the rails for weeks at a time. The spring compensates for these things.
But all this isn’t the main reason that a Commander uses a heavier spring.
Because the outside forces fighting the slide’s return are equal to those in the 5-inch gun, the goal was to insure equal momentum in the forward direction. Because momentum is a function of mass and velocity…and because the slide is, in fact, lower mass…it has to be moving a little faster when those outside forces start to fight it.
But wait! There’s more!
Because the Commander’s slide distance to the impact abutment is shorter than the 5-inch gun’s…the slide also has less distance…or runup…to the magazine, where it encounters its first significant resistant outside force…the spring has less distance to accelerate the slide to the required velocity to develop the momentum it needs to insure returning to battery.
This need for a heavier spring can be reduced or eliminated by seeing to it that the gun feeds as smoothly as possible, but the main culprit is the extractor. Believe it or not, the extractor can be the single most resistive outside force in the feeding phase if it’s not to spec in both deflection and tension. An extractor can stop a slide in its tracks just as it starts to pick up the case rim.
The problem is that mass produced pistols don’t get the attention to detail…the “fine tuning” if you will…that a gunsmith or a tuner can give it. So, they just stick in a heavier spring to make sure all the bases are covered. Over-engineered to compensate for the small variations.
I haven’t bought a Commander-specific action/recoil spring in over 30 years, and I never use the generally accepted “standard” 18 pounds in any event. For my Commanders…LW and steel-framed…I cut a Wolff 16 pound Government Model spring to 24.5 coils, and I’ve never had a problem.
This comes with a caveat, and this is important…so pay close attention.
The Commander recoil system must be of the original design…essentially a shortened Government Model system…and reverse plug/bushingless systems will not work with this trick. It will work with full-length guide rods as long as it’s not a reverse plug setup. Neither will it work in Officer’s Models, or Springfield’s 4-inch Champion…or in any shortened variant less than 4.25 inches.