The striker in a Glock is being partially held back, but not all the way. Theoretically if the striker were to be released it
could detonate a sensitive primer, but an actual failure isn't likely because of the firing pin block and the low tension placed on the parts in the partially-cocked mode. The greater danger regarding the Glock lies in the fact that the trigger only needs to travel a short distance to complete the cycle and discharge the gun. The only thing keeping it from happening is that tiny little lever on the trigger, and that is easily defeated if some foreign object should snag it and tug on the trigger. A Glock is very dangerous to carry UNLESS the trigger guard is completely covered and the gun held against movement. Most holsters are well-enough designed that the Glock is safe to carry, but the fact is that folks take it for granted.
Now regarding the 1911, people are nervous about "CnL" because of the fully cocked hammer which is fully visible, in addition to the extremely short trigger travel required to fire the piece. However, a discharge is still highly unlikely because:
1. If the hammer hook should fail the half-cock notch will catch the hammer.
2. The trigger can't move unless the grip safety is depressed.
3. The thumb safety positively blocks the sear from movement, and in a well-designed holster is highly unlikely to inadvertently snap to the off-safe position.
4. In a Series 80 or Kimber Series II there is a firing pin block safety.
So you have at least three safeties, four depending on the make of 1911. About the only way a 1911 can catastrophically discharge all by itself is if you have an old or cheaply-made gun w/o a firing pin safety and the sear nose somehow breaks off. Unless the part failed due to extreme age or was made of inferior materials, the only way it could happen is if the hammer were to receive a hellish blow from the outside.
And so, as long as you use a quality-brand 1911 with quality internal parts a CnL'd 1911 is easily as safe, if not more so than a loaded Glock.
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D. Kamm
USGI M1911/M1911A1 Pistols Website
http://www.geocities.com/M1911_M1911A1