Translation

KHR said:
You fell into the common trap of confusing 'canon' with 'cannon' ;-)

[Tomb] "Or mistyping it!"

'Schnellfeuer-Plasmakanone' would be korrekt.

[Tomb] Merci buckets, that's what we'll use. 

Strictly speaking, German compound words should not be hyphenated. So 
a German teacher would insist on 'Schnellfeuerplasmakanone', but most 
people do it for clarity.

[Tomb] You know, on the one hand, I think a language that builds more 
complex words by concatenation is a little unelegant, it has a 
certain spartan charm in that you can see the roots. It also 
restricts your base vocabulary a bit which might make the language a 
tad easier to learn. Still, as someone who enjoys the sound of 
Gaelic, I certainly have to enjoy German - glottal stops and all! 

'Kanone' is really an artillery piece and not used for man-portable
weaponry. '-gewehr' (rifle), '-büchse' (musket), '-faust' (as in
Panzerfaust) are alternatives.

[Tomb] In english, this is true too. The smallest canons are usually 
20mm or thereabouts. Yet Sci Fi is full of Assault Cannons, Storm 
Bolters, Portable Plasma Canons, etc.  (I think the distinction for a 
canon vs. a gewehr is made because plasma tends to hit pretty hard - 
higher impact, more damage). It's kind of taking a bit of liberty 
with the term. 

[Tomb] PS - thanks for your input! (I was actually thinking of your 
insights when I asked for help :)