Best silencing option I tried for the HC.
Only about 4" long so doesn't compromise the Carbine length so much.
Plastic (hard nylon/delrin type material) construction so doesn't add much weight.
The Parker Hale worked well at attenuation as well but is longer and heavier.
I got my male-to-male adapter from Chambers
at around a fiver.
http://www.chambersgunmakers.co.uk/Silencers.htm
Pics of HC with SB and PH silencers
User gives his Plenum plug away.
Silencer thread
The Logun is a fine silencer but the springs ring with the recoil.
IMO it's more suited to a PCP.