No.
Some hi-cap mags, Glocks come to mind, should be down-loaded a round or two to prevent spring over-compression.
Others like the 1911 or Browning High-Power for instance and be left fully loaded for generations without harm.
Repeated cycling is what weakens springs.
Not being left compressed, unless the mag design allows over-compressing them.
BTW: I have M-16 mags that have been loaded since I stole them from the Army in 1970.
I also have WWI 1911 & Colt Woodsman mags that were loaded with 1917 dated GI ammo & old pre-war copper case .22 RF when I bought the guns at estate sales.
They all still work perfectly.
rc
