Here ya go, polyphemus. The one on the far left is the standard since January 1918. The one in the center is one of mine, cut to roughly .070 radius...just slightly smaller than Browning's.
I found the one on the far right in a late production pre-Series 80 Combat Commander. It's got a slightly smaller radius than the now-standard 7/32nds.
Not sure if that was a fluke, or if Colt was experimenting.
Study these and see if it comes to ya how that radius would make a difference in the slide's delay and momentum. Don't let that single eye mislead ya, now.