Varies wildly. The other thing to bear in mind is that 40k tends to be even more extreme in its claims for the longevity of equipment than Traveller - ships, swords and body armour dating back four or five millenia are not uncommon, and some legacy items produced by humanity in the past are not far of traveller's ancient artefacts. The vortex grenade, for example, is essentially a pocket sized black globe generator.
Rinku's response is a pretty good one. Different areas of technology are more advanced, less advanced or almost totally absent.
Personal force fields, for example, are common enough that priests and officers of captain/colonel wear them almost as a badge of rank, built into some small jewelry.