Well I don�t know who at Colt answered that, but that�s weak. So here�s a way to do it that will give you best performance, and least wear to your gun. Choose your preferred load, whatever that may be. Shoot a couple rounds and watch where the empties land. You want them to land no less than 4 feet away, but no more than about 10 feet away. Any less and you could have a case of failure to eject if you have a soft load or manage to limp wrist say during a fast draw. Any more and you�re just beating the crap out of your slide. For most loads, that sweet spot seems to be around 16.5-20lbs for government models and Commanders.
And no, you don't have to change out your recoil spring every X amount of rounds. If the rounds start flying past that 10 foot mark, then it's time to change. Otherwise, it's good forever. Right off the bat a recoil spring will take a set and lose about 5% of it's weight. After a year or two it may lose another % or two, but after that, they tend to just settle into a consistent resistance and stay that way forever. If you choose your spring a touch on the heavy side to begin with, chances are you'll never have to change a recoil spring for the life of the gun.
Recoil springs are much tougher than magazine springs, yet it's been proven time and time again that most magazine springs will be good for life. There are some exceptions to that such as the Luger, which is HEAVILY dependent on magazine spring weight. But for most mere mortal guns, that's the case.
