Advice on Hop Rubber Checking/Changing

[Longshot]

I'm new to playing around with gun internals so need some advice on hop units and their rubbers.

I've taken my AK apart and now have a nice shiny blue Prowin hop unit in front of me. I've taken the barrel out. Now I just want to know whether everything is fine with the hop rubber, but I honestly don't know what I'm looking at.

This unit has a 'slide' type adjuster for the hop. When I'm looking through the unit and turn the adjuster from full off to full on should I be able to see the hop rubber emerge?

[Caveira]

Re: Advice on Hop Rubber Checking/Changing

You should see a small bulge appear as you put the hop on and disappear as you take it off.

Take the opportunity to check that it's lining up exactly square to the top of the hop unit as it can be off a bit if the barrel is rotated slightly.

[Longshot]

Re: Advice on Hop Rubber Checking/Changing

Right, I have no idea how this thing works at all.

Does anyone have any kind of guide with pictures/video?

[Longshot]

Re: Advice on Hop Rubber Checking/Changing

Right, I found a good one myself, here:

http://www.youtube.com/watch?v=0XfF9itDss0

Now I understand things a little bit better, but now I'm also wondering whether something is missing from my unit.

My unit has the 'sleeve' piece, which I've now correctly aligned, but not the small nubbin bit that pushes it down (the piece on the right in the picture below).

Does anyone know if that's because the Prowin AK hop unit doesn't actually need it? Because at the moment the plastic piece integral to the unit is what is pushing the rubber down.