Deployment timings/lifespans

Here's a question: 

We notice that in the 2180s, the NSL are using an SG-58, which 
suggests a 2158 deployment date (or perhaps design date?). What do we 
think is a likely length of time for someone like the NSL or NAC to 
issue a core piece of kit like a rifle to all of its forces? A year, 
ten years, twenty? And what do we expect rifle (or other small arm) 
service life to be before replacement with a newer design? Obviously 
the German weapon is over 20 years old. 

The french have the FA-75 which suggests (perhaps) a 2175 deployment 
(hence Gauss perhaps?). Maybe the next NSL weapon deployment will be 
Gauss. 

Interestingly, the UN has an ISW-82 (I think that's it...), 
suggesting its latest model designs are very recent. If one assumes 
that UNSCM are a small force, then it would be possible by 2183-85 
for most or all of the force to have received the new ISW. But 
perhaps the ESU or NAC would have far more problems equiping all 
their front line troops in the same period? 

Just something I'm mulling over. Thoughts?

PS - Mr. Brewer, you caught one doozy of a typo in that post to 
DAWGIE. And my response to that was "Oh My Gracious!". What I wrote