stethoscope for ns

A coworker gave me a Mccoy stethoscope that has never been used (still in the box). She was a medic in the army and no longer has a use for it. I am starting RN clinicals in the fall and want to know if this stethoscope will be fine to use for clinicals? It seems like everybody on here says that Littman is the best to have, but would it be ok to use the Mccoy and then once finished school switch to a Littman? Or don't bother and just buy a Littman from the beginning? I am on a tight budget so if I can save the expense I would like to but also don't want to short change my clinical experience with a bad stethoscope. I tested it out on my husband and son and it seems to work okay?