How close do I have to be to get mini-crits with the BackScatter?

From a quick test of mine, this is the max distance for Back Scatter mini-crits:

I put the Soldier under the center of the light and crept closer until the shot was a mini-crit. I don't have the distance numbers, but hopefully this image is descriptive enough. To me it looks like about half Sentry visibility range; if so that's 512 Source units (the point where the distance modifier in the damage formula is 1.0).

And just to confirm, you cannot get mini-crits from the front with it. The "and" in the description means both conditions must be met. (I was confused about this too at first.)