Mine does that hammer sound, too. I eventually figured out how to change gear "smoothly" so it doesn't make that sound and the shock...
Did you step on the clutch very fast/hard? Did you clutch before or after you release some gas? Also, did you release much gas when you change gear? Did you release the gas fast? In my case, these little things matter, enough to make the sound or not. You may try different techniques and see and feel if they help.
For your reference, I notice at the same time when my car makes that hammer sound, the RPM drops to usually 2k.
Oh, to answer your question, I don't know if that's normal or not.:12dunno