For anyone that is in the IRR, SMCR, or prior service ect. . I can't stress enough to know and understand your rights when it comes to employment. Some great sites are as follows:
www.dol.gov/elaws/userra.htm
www.osc.gov/userra.htm

You should also know your rights for the state you live in some will give more then others. It will take some time to search everything out but everyone should know their rights because your employer may not know.