These have been $35 at Classic for a while...for a $5 savings I'll stick with the tried and true Anderson aluminum lower. I'm not a fan of proprietary parts. How much of a weight savings? The GWACS lower saves 1lb over an aluminum lower with an A2 stock if you are looking for a lightweight fixed stock lower.
"Gen4 model is designed with a reinforced front trigger axle pin placement point to eliminate any fracturing during torque, when the receiver is in the break-down position." This tells me that for at least 3 generations now they have been having durability uses...no thanks.
Buy now and in three years sail them on here for $200 a pop.
You guys know what a popular "Magnesium Alloy" is? Zamak. You know, what they use to mold Jimenez/Hi-Point/Heritage revolvers/entry level Henry's/etc. I'm betting that this is what these lowers are made from, but it sounds better to market them as Magnesium than Zamak since everyone associates Zamak with throwaway pistols.