Airsoft surgeon hicapa nozzle + piston : very tight?

[Silverthorn]

Today, I tried to install a airsoft surgeon loading nozzle and the included piston head on my marui hicapa 5.1 and my marui hicapa xtreme.

With both those parts, the nozzle is very tight and has a hard time moving along it's path. In both cases, the nozzle return spring isn't strong enough to pull it back.

If I reinstall the stock marui piston head then it becomes acceptable (still a bit tight for the xtreme but it works).

Is this normal? Am I doing something wrong?

[RacingManiac]

It is tight, and I ended up not running its O-ring but some other ones around. But that was irrelavent later since the nozzle broke....went back to SD ones...