Do military/industrial tubes sound better than regular ones ?

No matter what it really all depends on synergy. I love my GE & RCA 5751 & 5814 Black Plates, I have them in Gray versions from GE & RCA as well. I’ve also accumulated At7’s, AU7’s & AX7’s from Amprex, Mullard,Slovak, Psvane, & Northern Electric that are now just sitting in a box. I sold the bugle Boys being I could. 

I’ve tried em’ all and found it’s all dependent on what you AND your system like. My GE 5814 Black Plates sound the best  in my System’s Preamp. 
GE 5751 Black Plates sound the best in my PhonoPre 

RCA 5751 Black Plates sound the best in my DAC. (For Output)

Thank god the preamp tubes should last a long time being these tubes are getting harder to locate, at a reasonable price that is.

A tube reseller once told me Black Plate Tubes handle the internal heat better, All I can tell you from my experience, I  find Black Plates to sound better and have a better synergy with my equipment. 

I have a ton of 12AX7, 12AT7, and 6SN7 vintage tubes, both military, “commercial,” e.g., FAA contract tubes, and regular consumer grade.  Military tubes are more rugged with more micas, support rods, etc. I don’t think military grade sound better per-se, rather I think they were simply manufactured at the hight of US tube production expertise from early 1940’s into the 1950’s and 60’s.  Once the transistor came into the picture, emphasis on tube production declined rapidly and quality suffered. 

That being said, my absolute favorite 6SN7s are a pair of 1945 JAN Sylvania 6SN7W and 1950’s Tung Sol 6SN7 GTWA. My favorite 12AX7 is a black plate Raytheon from 1950’s with Baldwin label. I have an identical back up Raytheon with the JAN anchor on it. They sound the same, no difference.

if you can find a high testing RCA black plates from same era, factory, etc, a consumer branded will be the same tube, same construction, same sound characteristics.  RCA Command were just pulled and labeled as such because they tested higher with closer matching tolerances, so I’ve read.

Buy two or three, don’t do like I did and go crazy buying and collecting hundreds of tubes that will outlive you and your children! Can’t listen to them all enough to wear them out.
 

@willywonka they are still used in the Russian space program

My experience is primarily with 12AX7 and 6SN7 tube types.

First, there are truly profound differences in the way different brands of tubes constructed at different times sound. These differences are repeatable. 
 

For the 12AX7 tube in my Marantz 7C, I liked Amperex from Holland or England, as they were a better fit than Telefunken as the latter made my preamp sound a little syrupy. Telefunken was a better match tonally to my Audio Research SP6B, though I still preferred the sound of the Amperex. I was anal enough in those days that I would bias the tubes in the SP6B every time I changed them.

My experience regarding the 6SN7 runs across several Schiit and Cary preamps. For the rich world of the 6SN7, the additional rigidity from extra supports, etc in the JAN and VT231 types results in lower microphonics and a greater sense of inner detail, sense of depth, and solidity and strength in the bass. It’s remarkable how there are distinct sound characteristics of each type- my Ken-Red VT231 black glass tubes really do have more solid and defined bass, and my 5692’s from both CBS Hytron and RCA have a smooth, liquid sound. My Sylvania tubes, ranging from Bad Boys of the early 1950’s to early 60’s GTB’s all share a bit of sparkle at the top, though the early versions sound better.

 I have not played much with new stock high-end offerings from China (scared off by reliability issues), but new standard production from Russia and China do not have the sense of inner detail, depth, power, or drive of the older tubes.

so yes, tube types do sound different!

@inna Some do and some don't. Something to keep in mind- all tubes, regardless of the source, should be vetted prior to use in high performance tube equipment! This means they should test good and also auditioned for noise, crackling and microphonics. Even then you'll find military tubes that don't seem to sound as good as consumer counterparts.