Since I got no reply on this subject I have to assume the person doing the testing is: A) using another ammo by mistake. B) His/her chrono is not working properly. C) Made other mistake.
1stMarine, you really shouldn't go assuming things like that. Quite frankly, I give up. This isn't even a discussion because your claims are so far off from what is KNOWN to be true.
Let me ask you this, anyway. How many rifles have you built? I've built a lot of them and I know what it takes to make an AR shoot straight. I learned a lot of it through trial and error, but I do have a good idea. I also know that a rifle built with the best components won't shoot worth a darn unless you feed it good ammunition.
When was the last time that you took a random sampling of M193, pulled the bullets and weighed the components to see how consistent they were? Did you ever measure the projectiles from the base to the ogive? I have. Some lots weren't too bad. Some lots were pretty bad. The point is that M193 isn't as consistent as you are proclaiming it to be. True match grade bullets vary VERY little in all specs that matter. Consistency is what makes accuracy and M193 just doesn't have it.