My .308 had the trans bar upgrade. Done for free at one of the authorized service centers. I'm unwilling to disassemble for a comparison pic, but it made a huge difference in performance and accuracy.
This rifle is a 2008 model with the HY serial number.
The biggest thing I noticed is that you can squeeze the trigger as you would on any rifle, without that nagging "remember to fully depress the trigger" repeating over and over in the back of your mind.
The next is that I have not had a single "fail to fire" since the upgrade, even after several boxes of shells.
I believe the issue was that there was a sloppiness in the trans bar assembly, even when you did everything right. As it was explained to me, the trans bar would have a tendency to drop or not remain consistent, causing inferior pin-strikes.
Whatever the hell it was, I'm so very glad they fixed it for me! My .308 is a pleasure to shoot now!