Pre-2008 Winchester M70, adjusted to a 2 pound pull weight, consistently failed when the rifle was dropped at a height of 12" on a tile floor with a 1/4" rug.
I'm an amateur tinkerer, so take my .02 for what's it's worth, but your report doesn't surprise me at all.
I'd never set an open M70 trigger that light and have found most M70's need to be in the 2.75b range to pass a drop test (if just adjusted "as is" from the factory - ie, no sear polishing/work or spring replacement).
I always drop them from around 2' onto concrete to test since it seems like a more real world test than carpet.
