I went to Lytle Creek a few weekends ago and found the road closed beginning right at the shooting range. I spoke to a Forest Ranger who said the road is impassible due to a 30' fissure that was created not too long ago by the rains. It is similar to what occurred at Angeles Crest Hwy. when it was recently closed due to storm-related damage. Although you cannot drive past the shooting range, you can park and hike up the trail.
Just a note, as you are heading down the road shortly after the shooting range, if you see a well-beaten hidden trail on the right with obvious worn tire tracks, don't drive down it to see what is there. That is unless you want to chat with a FR who will politely explain that, even though there are no signs not to take that trail, the rule of thumb is that if there is no sign saying it is okay, then don't take it. Apparently, that particular path is used regularly by people who want to dispose of stolen cars. After receiving a warning instead of a $75 ticket, in the future I will put a rein on my curiosity in that area.