Sound's like you had a great time in the wood's Mauser. Late Flintlock season has to be one of the most challanging and also the most enjoyable.

I see no problem with head on Chest shot like you took as long as the deer is close enough and you feel confident in your abilities. I have shot several deer head on and aimed right in the bottom of the white throat patch. They dropped intheir tracks and never moved. The bullet snapped the spine and it was a clean instant kill. Of course the deer were 12-15 yard's away.