Aligning a Samples BPM

Hi, I'm sure this has been covered, I'm looking using a 30 second sample in a track (it contains some percussion amongst other stuff!), however the BPM is very, very slightly out of sync, so after a few bars its starts to become annoying

Can anyone point me at a resource that will help me understand how to fix this issue?

I don't really use samples as a rule, so this is all new to me!

Thanks