Howdy from across the pond. I noticed that there was a comment about semi auto's and the noise the functioning caused. I have a Gemtech Trek
that I use on a 10-22. To alleviate some of the noise from the functioning of the rifle, I purchased a Heavy Charging Handle. I do not believe you
would be able to order one, but this is a website in the States that has some. http://www.brownells.com/rifle-parts/bolt-parts/charging-handle-parts/charging-handles/ruger-10-22-17-rimfire-heavy-bolt-handle-prod23314.aspx. It is possible to also mill out a piece of aluminum or steel to attach to your current charging handle to help slow down some of the gases and allow
more gas to go through the silencer/moderator/can. If you hold the charging handle forward on a 10-22 while firing, you will notice a great deal of change in the
sound. (you would have to manually function it)Hope this information can assist.