Quoted: If you are building a performance engine that is expected to  last and endure, are you going to use CAST pistons, crank and connecting rods? NO, of course not, you are going to spend the extra cash and buy FORGED because your know it will save you money in the long run and do what you need it to do. Most Cast lower receivers I have seen are only $10 to $20 dollars cheaper than their forged counterparts. It is crazy to compromise strength and structural integrity for such a small amount of savings.

While I agree that it makes no sense to save $10 on a weaker part (and usualy a less cosmetically pleasing part too), your comparison to forged engine parts is misleading.  Pistons, cranks and connceting rods are all load-bearing parts.  An AR lower doesn't have to do much more than hold the buttstock and magazine in the correct location relative to the upper.  If I were picking a rifle for it's ability to perform buttstrokes then a forged would be better than a cast, but then a steel receiver and heavier stock (i.e. M14/M1A) would be even better.

The most interesting thing in this thread is that someone out there actually SMASHES GUNS as part of their job. I pray for their soul.

Quoted: Quoted: An AR lower doesn't have to do much more than hold the buttstock and magazine in the correct location relative to the upper.   That is true but even the forged lower used in the design has been strengthened a time or two. Would pin hole (trigger/hammer and pivot/takedown) wear increase with the lesser metal used in the cast units?

I'm no metallurgist, but I don't think so.  Or rather, I don't think cast vs. forged is going to affect the wear as much as the actual finish.  A cast lower with good quality hard coat anodizing will wear better than a forged lower with a lesser quality anodizing.  In the case of DPMS, their teflon coating may also help to reduce wear at those points.