The dowel pins used to secure the blocks and barrels are of course an interference fit. ComBloc pins are larger than stated size and the holes to receive them are the stated size. This is a different assembly system than is used for general machine assembly pinning.
When the rifle is assembled the pins are pressed in and driven in from the right-hand (charging handle) side. The ends are often a bit swollen on this side; so when pressing them out it is normally the best practice to apply pressure to the left-hand side.