The Godfinger’s bullet spread isn’t quite like the Bekah’s (in that the bullets fan out laterally after a while); the Godfinger’s extra bullets stay in line. I believe the Godfinger has two mechanisms at play, and I haven’t looked after trying to stack them (which would be a little difficult).
First: bullets that hit an enemy will split into a number of smaller ones (five? Derch turned me onto this, and he can confirm the number). Those continue on pseudo-B0re style to other targets downrange. Fighting a Constructor? Come at it from the side so the turrets and body are lined up, and you’ll see this in action.
Second: the longer a bullet is in the air, the more bullets appear in-stream. For shots against single targets, you can get up to 14 extra rounds, but the distance is pretty freakin’ far. (I see lots of people using sniper rifles in the role of an assault rifle, for example: the Godfinger would be bad for this).
If you were to line two targets up at long distance (or shoot a distant target through a much closer target), I’m not sure these would stack? It seems like they would, in which case the damage would be, well, even more insane. If you just use it like a normal sniper rifle, and aren’t maximizing your distance from the target, I might consider something else.
As with the Bekah, this lends itself to abuse by Amp shields, since those pellets are unlisted.