Hi Ron,
Deactivation is quite extensive.
The barrel or chamber are pluged and welded.
Sometimes the bore is drilled out aswell.
The 'ramp' between the clip and chamber is ground down - the firing pin and breach block are also ground back, this stops a round being 'picked up'.
Sometimes most of the interlocking rails are ground away.
That's just about all that is done...........
I think Tachfoley (spelling?) posted a very comprehensive series of photo's
showing the different stages of deactivation.
Sorry, but i cannot find it now.
That reminds me, John Sabato asked me to do the same thing for the MP.40.
Well i have a decent camera now, so i can get that done.
All the best,
Steve.