It seems to me that any member of the Armed Forces who has been guilty of forgery and firearms offences would be in serious trouble.
Mitigating factors:
1. By some accounts, he's a nice chap.
2. No malice seems to have been intended.
There are however some aggravating factors:
1. This was an commissioned officer, and the forgery calls into question his integrity.
2. These offences are related to deployment to an operational theatre, with its attendant dangers, not a backwater of the training establishment.
3. The ammunition was kept for seven months, not a week or two.
Imprisonment and being cashiered seems appropriate to the severity of the offences. Certainly an NCO would be looking at MCTC for this, therefore the sentence for an officer must be no less.
Maybe the time in the Greybar Hotel will be an opportunity to reflect on certain choices, and having paid the debt to military society, he can proceed with life from a new perspective. He will be free to choose his own future, and make the best out of life, like the rest of us.