Help Identifying Russia 1914 Scott B5A?, B10? B8A?

I'm trying to develop my identification and description skills, so I'd like to ask the pros out there for some help on these 1914-15 Russian stamps:


This stamp looks to me to be B5a MNH. It has 13.5 perf, which rules out B5. And its colors look more like "red brn & dk grn, straw" than "orange brn & gray", which rules out B9.


I identified this stamp as B8a, because it is perf. 13.5, ruling out B8. It could be B13, but I'm not sure how to distinguish between the "" of B8a and the "dk blue & brown" of B13. B13 is also printed on white paper, and the paper looks somewhat off-white to me. The upper left corner is stained, which is matched by some kind of residue on the back.


This stamp I identified as B10. It is perf. 13.5, and more closely matches B10's "car & gray black" than B6a's "mar & gray grn, pink". However, I'm not sure if it is "white paper" or not. This stamp also appears stained in the upper left corner which is matched by black residue on the back.

I'd appreciate anybody's feedback on whether I'm on target or not. I understand scans are never as good for judging as the real stamp, but I'm still interested in hearing your comments even with that caveat.

Thanks.

I agree you have 1) B5a 2) B13 because B8a is on blue paper and that paper is white, even though stained and 3) B20 because the paper is not pink and the paper in your pick looks white to me.

Looks like the second and third stamps, had at one time, stuck to the face of other stamps. They were probably stacked and stored in a place that was hot or damp.