I ran a 16# spring in a dedicated IDPA 1911 for years. Carry guns get a 18# Wolff or ISMI springs. Springs should be chosen based on your ammo and what works with your gun. Larry Vickers recommends 17#-18# springs in 5" carry guns FWIW. Not many folks know more about the workings of a 1911 than LAV. I used to use the Wolff 16.5 variable springs with good results for the IDPA gun. Seemed to last longer than some cheaper springs. I buy the 10 packs from Brownells.

Mark
A07211
downrange360.blogspot.com
Unrepentant IDPA purist

"Nine targets isn't a defensive scenario, in my book, that's combat."