Black on the outer-wing is variable but not dramatically so, far less than in Vega for example, at least in my experience in Kansai, but that could be down in part to a smaller sample. By far the most frequent pattern of black running inwards along the trailing edge is a sub-terminal band on p5 with a notch on the outer web of p4. Many birds are darker but lighter seems exceptional, the lightest birds I've seen had a broken p5 band with no p4 notch, well within Vega territory, but there are very few of them. At the darker end of the scale; notches on both webs of p4, or even an unbroken band aren't unusual. A notch on p3 is unusual on birds that don't show any (additional?) signs of immaturity but even Vega can show a p3 notch albeit very rarely. There's invariably a fingernail or slightly broader white moon between the sub-terminal black and the basal grey of the inner web to p7 and less often on p8.
The p10 mirror is generally fairly squared across the proximal edge and oval distally. The tip is black usually with only a small apical spot, this can be slightly larger and infrequently gulls with the mirror breaking through to the tip do occur. However on many gulls the apical spot is tiny or absent. At its largest the p9 mirror can be fairly conspicuous and rounded or it can be very small, though even the smallest can straddle the vein. Birds with no p9 mirror aren't unusual.
More extensive black extending towards the bases of p7-8 is the norm and differs from the vast majority Vega, though some do match this. There's a broad swathe of black along the leading edge of the Taimyr wing whereas Vega shows more extensive grey in the bases of p7-8 and a narrower black leading edge. As well as being obvious in flight, this can be easily seen at rest where Taimyr shows a solid area of black below the tertial fan whereas Vega typically shows grey above the black leading edge.
A sub-adult with prominent black streaks in the greater primary coverts and an absence of moons. I'm uncertain whether the latter is age related but I've never seen an adult totally lacking them. I confirmed immaturity by the extensive white tip to the bill and very limited red with a black spot on the gonys as well as a dark crescent on the upper mandible.This is the same bird as the first head shot on the previous Taimyr Gull post.
A pale-end bird with no black on p4 and a narrow moon on the inner web of p8. A p4 notch is the norm and typically moons only reach p7.
This adult lacks a p9 mirror and moons only reach p7. Broad black strip on the outer web of p8 almost reaches the coverts helping create extensively dark outer primaries. A first winter Taimyr (and crow) in pursuit of its fish.
A fairly typical bird, slightly elongated p10 mirror, the small p9 mirror straddles the vein. No moon on p8 which has extensive black towards the base and bleeding into the inner web creating a broad dark leading edge. This bird has a broken band on p4, most have just a notch on the outer web though that is often larger than on this individual.
Another with no p9 mirror, black extends across the inner web of p8 and the outer web of p7 is black almost to the base. This is darker than most across the outer primaries.
About as large p9-10 mirrors as I see and the broken p5 band put this bird towards the pale-end of the outer primary spectrum even though it doesn't have a p8 moon. The bird on the right is more typical.
Possibly a sub-adult judging by the dusky mark across the top of the upper mandible. The same bird below.
A few flight shots of Vega for comparison.
Unlike this gull many Vega have a complete sub-terminal band on p5 and don't have the mirror breaking through to the tip on p10, thus this bird is towards the pale end of the range, however Vega like this are frequent and that there's significantly less black in the bases of p7-8 is typical and creates a narrower black leading edge.
This Vega has extensive black towards the bases on p7-8 and looks similar to Taimyr in that respect. However the p10 mirror is much larger than typical for Taimyr with an incomplete sub-terminal band and the huge rounded moon in p7 and broad white tips to the inner feathers are typical of Vega.
This quite different to Taimyr with the large p10 mirror breaking through to the tip, a large p9 mirror and lengthy grey tongue. There's a broad moon on p8 and only a light sub-terminal band on p5.
At the palest end of the scale very white-winged Vegas showing a thayeri- or near thayeri-type pattern are uncommon but not rare. This out of focus bird wasn't the target so below I've added an older image of a bird in Osaka.