(2 images) Larus fuscus fuscus 3cy C4XR, July 09-17 2003, Tampere, Finland (61.33N 24.59E).

C4XR was ringed in Hauho, Finland; ringed as pullus on June 30 2001.
Recorded at Tampere:
2003-05-31, 2003-06-01, 2003-06-03, 2003-06-07, 2003-06-14, 2003-06-15, 2003-06-16, 2003-06-17, 2003-06-18, 2003-06-20, 2003-06-22, 2003-06-28, 2003-06-29, 2003-07-05, 2003-07-06, 2003-07-09, 2003-07-10, 2003-07-11, 2003-07-12, 2003-07-14, 2003-07-15, 2003-07-16, 2003-07-17, 2003-07-20, 2003-07-26

Larus fuscus fuscus in 2cy often returns with completely replaced primaries and secondaries. In 3cy, fuscus more often shows a clear division between fresh inner primaries and older outer primaries, the inner primaries often showing neat white tips and the outer primaries often second generation-like with rounded tips and paler bleached brown. The arrested moult in the primaries is often reflected in the secondaries and (to a less extend) in the tail-feathers as well. The older tail-feathers (often R5 is older) still show a broad dark sub-terminal band.
3cy fuscus often have some black markings on the bill, which is otherwise much adult-like, with a clear red gonydeal spot. The colour of the naked parts are adult-like as well. 
The scapulars in 3cy are often completely adult-like, lacking internal patterns; plain blackish grey with a mahogany hue on the older feathers. Most wing-coverts and tertials are adult-like blackish grey as well, but often 3cy birds show some very bleached pale brown wing-coverts, normally in the greater covert bar and in the upper rows of the lesser coverts. These bleached wing-coverts accentuate the jumpy sequence in the last wing-covert moult cycles, as there is often no clear pattern in location of these bleached feathers. Head and body feathers normally are snow-white by July.

C4XR was ringed in Finland, now in 3cy. This 3cy fuscus has arrested primary moult prior to northbound migration: there is a clear division in the visible outer primaries between P6 and P7. The four outer primaries (P7-P10) are bleached brown and worn second generation, but there is a mirror on P10. The inner primaries are third generation, P1-P6 are much darker with small white tips.
Note the fresh rectrices, they appear all white and note the limited dark markings on the bill and the retained bleached wing-coverts, typical for 3cy birds. All secondaries fresh as well.