Maybe a Tristar stock can be made to fit if you're a stockmaker... 12 ga mod 12 stocks won't fit 16 ga model 12s in any conventional sense. I would guess the OP was looking for a fit without some heroic modifications.Beg to differ . 12 ga. stock will fit a 16-20-or 28 ga. .
Wood will be proud where it meets the receiver . Depending on how picky one is it can be sanded down to appear it was made for the gun .