I haven't talked to Newt for a while, but I'm guessing he's gotten slammed with military orders in the last 6 months, and he's understandably having a hard time filling them along with his civilian orders at the same time. His shop is small, after all, but Newt's knives are designed and made first and foremost with real soldiers in mind and I think he puts a priority on military orders whether they come through a service branch or an individual soldier.
Again I don't know for sure, but given what I know about Newt, this is a reasonable speculation concerning his present fulfillment problems.