I haven't seen or heard of any delays for federal government workers 1099-Rs because of the shutdown.
But, the due date in general for Form 1099-R to be mailed was Jan 31, 2018. So, it's still possible it may be in the mail right now. In fact, I just received mine today in the mail.
If you don't have it within a few days, then you should contact the trustee of the account
