Grandpa wasn't prone to hyperbole; I believe him.
And it was an excellent lesson for me, though it took 15-20 years for me to learn it. More often than not, stories are told for a reason, and sometimes they're only told once. I miss Grandpa, if he was still around I'd listen more and talk less.
If you’re interested in your grandfather’s experiences, I’d recommend you read Citizen Soldiers, by Stephen Ambrose.