I have the Millett in 6-25. It is not bad. When I built up my 308 I was also looking to stay in the $500 range. I have used it for up to 600. I am currently look to replace it with a Leupold Mark 4.
A pistol can be any size as long as there is not stock on the buffer tube. I have shot an AR pistol and did not care for it, that being said I do have 3 short uppers and I am working on the 4th to go on my SBR.
I think I read forged alum not weaker billet 3 times. Because they have Facebook? Am I the only one here who does not care if my gun maker has Facebook?
They made me a 20" for an Iron Ridge upper, DPMS style. What I thought was weird is that it uses an Armalite gas tube. It is a bit longer than a normal rifle gas tube.