Do military/industrial tubes sound better than regular ones ?

Yeah, no doubt, NASA grade, medical grade, scientific grade. But also for guitar amplifiers, organs, TVs etc.

There is discussion of what a military tube really is so I'll add my understanding.  Military tubes generally have a military designation like vt-231 and often have JAN (joint army navy) on the box or even on the base.    They were made for a military contract and are generally the same design.  For my amp, the VT-62 is the 801A.

So I don't give military tubes more respect unless they come with a reputation.  The 6SN7 tubes have been studied to death and many of the military tubes are considered great but not because they have a military designator, because people think they sound better.  

Jerry

Be careful buying " medical" and " instrument" grade tubes.  Especially 6922 as they were used in a lot of test equipment.   Many are not NOS , they were pulled from gear as it was phased out and replaced  by solid state.   "Pulls" as they are known.  Many of those tubes were robust and still tested as new when pulled.  Plain white boxes and weak lettering is a red flag. 

Military vacuum tubes are built to specifications that ensure resistance to failure in high vibration environments and tighter tolerances³. They are not necessarily for the military, but are manufactured to meet these requirements³⁵

^{Perhaps tighter tolerances may impact the sound, but I believe the ones labeled for the military are no different than the ones labeled for any other use, probably coming off the same line, only labeled differently.}

Well, Brent from Audio Tubes has both regular 12AU7 RCA black plates and military/industrial ones, all from 50s, not sure early or late 50s. He also calls industrial Command Series. I have regular ones installed, so I could order a set of military/industrial, burn them in for 100 hours and then compare. Return them if I hear no difference and lose 20% which would not be much, those tubes are $99 each and I would need three of them. I just don’t want to start with this and don’t want to buy more tubes right away, last week spent $450 for a matched pair of 12AX7 NOS Mullards longplates from 50s. They are excellent tubes, hard to find, so I bought a spare pair from Brent.