I am considering getting either a Kalash RK-01 or RK-06.

If I decide on the RK-06 I want to use it as a marksman weapon. So I will need to upgrade the barrel/hopup assembly. Which hop-up unit and rubber would you recommend? I need to stay under 400fps with 0.2gr BBs.

No need to change the stock hop up chamber/rubber komrad.

But that's for me...let's wait for some advise from our gurus

agree. especially since 400 is your fps limit.

what you really need to do is fine tune your hop adjustment. check out the tech refs in this section. visit the threads on the hop tweaks.

and :

komrad RZA

komrad zT, komrad RatelZA is from SA

oops, my bad. fixed.

Thanks for the welcoming guys!

Play with your stock hop-up. After that when the time comes that it will need replacement then you'll know.

And welcome!