Just so I get this right...

A battle servitor has a BS of 30 and (in this case) equiped with a Heavy Bolter (range 120) so within 60 meters he adds + 10 to BS for short range and then adds + 20 for full auto giving the servitor a total BS of 60, and each degree of success means an additional hit.

Am I correct? this is a very deadly warrior indeed

It appears to be correct. In the WH40K RPGs, Full Auto weapons tend to be more accurate per attack (less so if you figure out accuracy per bullet/shot, but that's a worry for the supply clerks) regardless of range.

Why would you think a combat cyborg with a heavy machine gun and a great big hopper of ammo is not a deadly warrior?

Great, thanks for the confirm