Tikka like Sako are owned now by Berretta ................................................. hence the plastic bits.
They use the same barrels for both Tikka and Sako but Tikka T3 comes in one action length the Sako has different lengths.
The T3's I have shot do perform very well a friend has one in 222 Rem and a T3 tactical in .308.
The plastic bits seem to be popular with the younger crown as does matte bead blasted finishes rather than proper polish and bluing
and of course this cheaper blasted finish is very popular with the makers because it's quick and cheap to do.
Like with the Rem 700 there are companies making steel parts to replace some of the plastic bits like bolt shrouds for the Tikka T3.
The Tikka T3 is very popular here in the UK despite the price being way higher than you will pay in the US
.