Unfortunately, missing deadlines on builds happen. Sometimes they are for legitimate reasons and can't be avoided, other times it's for BS reasons and customers are flat out lied to.
IMO, if a build deadline is going to be missed, it is up to the gunsmith/company to contact the customer and give a truthful reason. Even if the reason is one I don't care to hear, being honest about it is always better than some BS story.
I had a bolt gun build a few years back that I was told one year on. It took some heated discussions and three years to finally get my gun built. If that wasn't bad enough, after three years and finally getting the gun, it didn't function properly and required further work. As one could imagine, I never used that gunsmith again.