G'day Sniff, and sorry about the delay in replying to you Beanflying (you asked me this a few weeks ago), I wasn't ignoring you 😉, just been busy with work and the kids. I haven't done a lot of measuring re the grind retention, and I don't have a hopper lid that fits anymore, so I can't use it as a 'pump' to help flush out the extra grinds. Having said that, I had to remove the top burr and clean out the burr housing yesterday and there was a heap of ground coffee in there. I'd estimate about 14g, after about 2-3 weeks worth of grinding. This morning I put two scoops in to the empty grinder (about 16-17g) and I got just under 15g out, so there doesn't appear to be a great deal of retention per shot, but it seems to build up after a while. I was fairly slack with my cleaning routine until now :-[. I haven't used a vac on it yet, just using the 'continuous dose' to pulse out ground coffee at the end of the day. All the best, Steve.