Tuning AEA shim tune? 35 cal?

Well I did a search on depinger. I assume it is something to deadening the sound in the air tube. I found some post as to guys sticking a small bottle brush inside just a little larger then the

Inside of the tube. I assume it was to help deadening the the ring, if indeed I,m understanding this correctly. If that is the case, then why could you not rap some rubber 

sheeting around the OD of the air tube. I even thought of taking a small bicycle tube and stretching it over the tube as a damper. Problem is the air chamber OD is like

1.6 inch. I do not think there is a inflatable inertube that small. Guys I,m new to this and maybe ask some strange questions from time to time so please be patient with 

with me! Fly😀
 
I made a de-pinger out of Delrin. It's just a closed cylinder with holes drilled in one end. Put a couple of 1/8th holes in the closed end and an o-ring to seal it. I did not put the holes in the center and drilled them at an angle. It werqs extremely well. 

If this is the route you take you need to remember that your de-pinger will also be your plenum. 

So make it to suit your power requirements so you don't choke off your power like I did on my first one.

https://hillairgun.com/product/hill-airgun-pcp-depingers/
 
I have the Challenger Bullpup, so there might be a difference in shim washer size, but here goes:

I made a washer out of a steel for additional hammer weight and only a little additional spring pressure. My washer is .835" o.d. by .560" i.d. and .118" thick. It weighs 67.3 grains, nearly the same as four of the AEA aluminum washers. AEA washers are only a few thousandths larger and .080" thick each. The slightly smaller dimensions were made for clearance for easier removal because the aluminum washers were a tight fit and required complete disassembly to remove. I also found that the stock configuration from the factory produced more consistent and tighter shot string. So after various testing of the AEA washers and my steel washer they are not currently installed.

As far as a depinger goes, there is a guy who successfully installed a section of wire loom ribbed plastic in his AEA. This wire loom is available at auto parts and hardware stores. This is probably a better solution than a brush because the brush has the potential to loose bristles after a while.