Oh Boy....this is probably going to turn into a long thread.
I own several Tikkas. Truthfully, I have never had any problems with the plastic bolt shroud. I always wondered if anyone else ever had any problems. Over the years, it happened to no one that I know about. As such, you are the first, and I'm sorry to hear that it happened to you. I guess it is inevitable. And I guess you can say that every gun part breaks now and then, whether it be Tikka, Sako, Remington, Winchester, Browning, Kimber, Ruger, etc. However, given that there has been so much debate and discussion regarding the "plastic" on Tikka rifles, I would imagine that this thread will likely be quite active, and perhpas more so than is deserved, I don't know.
The bottom line is that your bolt shroud broke, and you need a new one. Unfortunately, since this has never happened to me, I don't know where you can get a bolt shroud. However, I guess that I would recommend contacting a local gunsmith and see if he can get one. I'm sure that an authorized beretta dealer would be better, but then again, Gander said that it takes them forever to get parts. I don't know why this is.
Zachary