Axial play, how much is normal?

I just measured it and it is only 2mm per side of movement, so just over 1/16 of an inch.
sure felt like it was more than that ha ha. (sometimes when i go around a corner slowely i hear a small "thunk" this must be the axle moving i guess since i have checked everything else) So is 1/16th too much or is that within spec?
Thanks, Wilco.