but if 4 were heard then there should be 6 holes in the body. (assuming he hit with all 4. )
Um, that's assuming the first two shots (from the "new" FBI agent) were of any consequence to the shape-shifting soldier. Perhaps the two shots glanced off, or passed-thru. It's not like we have a clear handle on what these shape-shifters are capable of. The speed and jumping ability are clearly off the charts (the escape from Olivia's room).
Not to mention the other assumption you already mentioned (that all the audible shots hit the "nurse").
Missing bullets is hardly a problem.
I think in the end this was just an easy way to get rid of the character as they didn't want to extend his contract.
This is just an easy way out? I realize the show was asked/told to cut production costs (and cutting a character is one way to accomplish that), but I can't fathom how this storyline is just an easy way to write Charlie out of the show. Wouldn't it have been easier to not include Charlie's character at all anymore? Judging by the spoilers/teasers at the end of episode, the actor will clearly be in an another episode, if not a few more. Besides, this elements of the story fit perfectly with what we've seen thus far in Fringe.
Doesn't feel contrived at all (well, aside from the Congressional review).
Anyway, I enjoyed the show, and I'm glad it's back. Fringe is definitely one of my favourites.