So what does "Targeted after assembly" mean?

[Rick Cummelin]

Thanks--as a military guy, it seems strange to me that the arsenal would stamp a barrel for something that the soldier would have to re-do when he received the rifle.

They were looking for really accurate rifles that could be made into and then sold as National Match rifles. Those that didn't pass the test became regular service rifles. Many late SA service rifles are stamped with the T, but virtually all NM rifles have the T stamp.