Need some help w/ the Vltor A5

[TCBA_Joe]

I recently traded a buddy my fixed stock for his collapsible and Vltor tube that he was having issues with on his .308.

I just compared it to another RE of mine and it seems to be noticeably longer. It's on an orphan lower so I haven't used it yet. I think I might know where the buffer is (in my buddy's .308 AR) but I need to know if there are any obvious markings. What is the length of a vltor A5 buffer? Of a .308 AR rifle buffer?

Also, it takes a rifle spring, correct? We were both under the impression this was a just a Vltor branded tube.