Nunas wrote:I can't comment from experience with this screen, or the with machines that have screws holding their shower screens in place. But I have plenty of experience with sintered metal puck screens; I bought a couple of generic ones mostly to prove they do nothing , only to keep using them for some years .

One of the things a sintered metal puck screen (n.p.c. thin puck screens) does is to keep the puck somewhat compacted during the preinfusion phase. It takes up the space above the puck, or much of it. When the coffee grains expand, they are then forced into any voids in the puck. I believe that this is why some folks report less channeling when using a sintered metal screen. This one would leave a space between the periphery of the shower screen screw and the edge of that big hole in the centre. I'm not at all sure if this would have any meaningful effect on the foregoing limitation of expansion, but it must have some. My guess is that it would work, but with an unknown amount of degradation in effect, compared to a standard puck screen.

Another noticeable effect of the sintered metal puck screen is to prevent coffee grains from "swimming upstream", after the pull, as the puck rebounds from the intense compression of the pull. Again, depending on the amount of coffee that might get past the space between the screw and the hole, I'd expect some slight degradation, but have no idea whatsoever if it would be a meaningful amount.

erik996 wrote:I just started using a normcore one with the hole with my GS3. The group screw does protrude and leaves an indentation in my puck, so there isn't enough headspace for a standard screen. I could get a bigger basket, but the screen with the hole has calmed my shots down