(2 images) Larus fuscus fuscus 3cy C4CM, July 12-17 2003, Tampere, Finland (61.33N 24.59E).

C4CM was ringed in Virrat, Finland; ringed as pullus on July 04 2001.
Recorded at Tampere:
2003-06-20, 2003-06-22, 2003-06-28, 2003-06-29, 2003-07-06, 2003-07-09, 2003-07-11, 2003-07-12, 2003-07-16, 2003-07-17, 2003-07-20, 2003-07-23, 2003-07-24, 2003-07-26, 2003-07-27, 2003-07-31, 2003-08-02, 2003-08-09.

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.

C4CM was ringed as in Finland, now in 3cy. This 3cy fuscus has the two outer primaries (P8-P10) bleached brown, with the small white crescents almost completely worn away. P10 lacks a small mirror and therefore is most probably 2nd generation. The seven inner primaries have been replaced prior to northbound migration. Primary moult was arrested at P7 this spring, leaving a clear division between P7 and P8.
Note the dark markings on the cutting edge of the bill and the retained bleached wing-coverts.

See also: C8CM, present on Tampere dump, July 2003.