Good morning Chris,
According to my records you are looking at it backwards. If you look at D1.8-2009, Clause 6.10.2.1 & 6.11.3 then sample #4 is equivalent to 500 uin. Then, looking at D1.1-2008, Clause 5.15.4.3 sample #3 is 1000 uin and #2 is 2000 uin. So, I would speculate that #1 is about 3000 uin.
The paperwork that comes with the samples of C4.1-77 (which I have right here in front of me) does not explain/state the relationship between sample # and uin.
Have a Great Day, Brent