Some thoughts after reading all the posts.
Felony endangerment means someone, or at the minimum a inhabited dwelling, was threatened by careless use of the firearm to the point of criminal negligence. It would seem to me if your stepson would have spent some time in jail instead of just having his firearm taken and issued a citation. He was issued a citation with a court date wasn't he?
In my experience, going to the sheriff's office to obtain a copy of the report will end up with you getting a heavily redacted report with things missing like the reporting party's name, and all the other pertinent documents like evidence lists, etc. Wait until the arraignment. Your stepson will get a complete report as part of discovery. Normally that is given to his attorney, but if he shows up without one he will get the discovery so he can go shopping for an attorney. Insist on getting the discovery. In California he would normally get 7-10 days to get an attorney after arraignment.
One of the things that stands out is the deputy's assessment there was insufficient backstop to be shooting where he was. The deputy did not say bullets were landing in the vicinity of a victim or striking the victim's house. The deputy has rendered an opinion about the sufficiency of the backstop. Rather than take the stance of proving the backstop was sufficient, let the prosecuting attorney go through the trouble of qualifying the deputy as an expert on range safety, backstop design, the lethality of bullets at extended ranges, what elevation a handgun has to be fired for the bullets to impact a quarter or half mile away. If all this is an issue in the prosecution, quietly prepare a defense for every possible claim the deputy makes in court. Example: The deputy claims your bullets were hitting around the victim's house a half mile away, ask if he knows what elevation in degrees a 9mm handgun has to be raised to carry that far. Of course, know the answer.
One thing to remember. A prosecuting attorney with a weak case will try to plea bargain. He will count on your stepson's fear and inexperience in these matters. If your stepson is not a good poker player, he had better have an attorney who is. Accepting a misdemeanor plea for careless use of a firearm may affect his ability to buy or possess firearms for some definite period of time. California prohibits possession of firearms for convictions for certain violent misdemeanors for ten years. Also, a guilty plea for a misdemeanor will certainly include probation that will limit or prohibit your stepson from possessing firearms. Research this very carefully before accepting a plea bargain.
The prosecuting attorney may offer to dismiss the case if your stepson stipulates that the deputy had probable cause to arrest. If your stepson agrees to that, he gives up all claims for damages and compensation for attorney's fees.
If your stepson does get a dismissal, make sure the court orders the sheriff to give his pistol back to him. I have seen instances where this does not happen and the sheriff gets really petty, saying he won't return the firearm without a court order. That just wastes your stepson's time and will inevitably cost more in attorney's fees to draft a motion for said court order.
Good luck.
