Originally Posted by
Tokarev
If I remember the Series 80 evolution correctly, Colt went to a safety shelf instead of a halfcock notch to help prevent discharge in case the gun was dropped on the hammer with the hammer lowered to the halfcock notch. It was a common occurrence for people to carry a 1911 with a round chambered, safety off and the hammer resting on the halfcock notch. A drop from waist height was enough to break the halfcock notch and allow the hammer to impart the firing pin with enough force to fire the pistol. The safety shelf is farther forward so the hammer is almost at rest and is also more robust. Springfield uses a version of the safety shelf also.
Anyway, the upswept shape of most modern beaver tails should help protect the hammer in case of a drop.