Grik is right when ranked up only the front rank can fire
When on a hill the second rank can fire also
With my Gnoblars I deploy in 2 ranks of 12 meaning I get 24 shots 2x 12
The Gnoblars are so cheap and disposable with careful movement you can get of 2 rounds of shooting (yours and a stand and shoot) before anything even hits your line( at which stage the Gnobs will die)
The way I use my gnobs is to push them well forward of my battle line covering most of the battlefield(I have 3 units of 24) this generally manages to clear out any small units trying to flank me and has been known to take out elite cavalry units, and expensive skirmish units.
Once all the skirmish type units are dead I let the gnobs get charged, do a few wounds on the big block units hopefully at least 1 wd to lose a rank before my Ogres hit on the counter. Just remember to leave a large gap between Gnobs and Ogres to account for overrun.
<img src="https://www.heresy-online.net/daemons/adoptables/888.gif" alt="Broken Daemon Image" /><br><a