I remember polymer cased ammo available as surplus (foreign I think) 30 years ago in LGS. I am pretty sure 308 was available, possibly 5.56 and/or 7.62x39. This stuff all had brass heads. I would have purchased and tried some, but I have never owned a weapon chambered in any of the three cartridges mentioned.

People who choose to brew up their own storms bitch loudest about the rain.