Weapon focus bullets, Would they work? Options

[spica2501]

While shadow running last night, my runner group had to sneak into a facility that was guarded by both astral mages and red samurai. It would have been easy to hide from one or the other, but not both at the same time. This situation brought up the point that it is extremely hard to stealth kill astral mages when they project in groups because weapon foci are melee only and engaging them in astral combat or mana bolting them is fairly conspicuous. Someone, I don't remember who, suggested that one make a single arrow or bullet into a weapon focus so that it would be dual natured, and therefore able to shoot astral mages (though, since it is not a melee attack, the focus' rating wouldn't add to the attack). If this does work it would be very expensive, seeing as each bullet would cost several thousand nuyen, and one would have to make said bullets out of tungsten or depleated uranium so that the bullet would not deform upon impact and therefore be recoverable using an implanted RFID tag.

My question is, would a weapon focus bullet/arrow work?