I say stats like this are more likely:
Pros:
50% larger magazine size(=60 or 20 more than normal) (possibly increase the mag size some more, but 60 is a good start)
+30% projectile speed
at max health +10% accuracy (if extra is included up to +20% at max over heal)
Cons:
Accuracy grows worse as health decreaces
-15% movement speed
No reserve ammo

extra: Fire rate takes time to speed up, starts slow and gets faster the longer fire is sustained.(min at -15% fire rate to max at +15% fire rate. Takes around 3 seconds of continuous fire to reach max)
(possible extra: While overhealed, accuracy is increased)

ITS LIKE TURNING YOUR MEDIC INTO A MINI (much squishier) HEAVY!
Thought of this idea so that medics can have more offencive cappibilities than with just the blutesauger. Also off topic from the syring gun, the heers helm would go perfectly with that kevlar vest.