I see in many post that people are putting in 17+ gms into a double shot or another technique of leveling off from the rim of the basket. When I try this with the stock rancilio basket, it always overfills causing the puck to touch the grouphead. what am I missing?

what am I missing?

A bigger basket...?

Seriously, the best mass of coffee to use is the one that gives you the best taste. 17 grams in a Stock Rancilio double basket is a huge updose and could take a ball peen hammer tamper to get it all in there.

How much you can get into a basket and pull a decent shot (mechanically, flavor is another question) depends on the headroom or head space of the group head. They vary from machine to machine. Some have suggested checking the limit for a specific basket and group using a US nickle (~2 mm thickness) on the tamped puck, locking in the group, removing it (without pulling a shot), and seeing if the coin left a depression on the puck.

In my opinion, it's best to just use your basket according to its capacity without hitting the screen. The numerical people are dosing in their basket shouldn't matter that much. You can achieve almost similar result by pulling a tighter shot(more ristretto) or less volume. What matters most is the brew ratio. For instance, if they're updosing to 17g coffee to get 34g shot in 30 sec, theoretically you can achieve the same result by pulling 28g of shot from 14g of ground coffee in 30 sec. So what you're missing is probably just the volume. Probably not so much in term of flavor(at least not significant as compared to other variable in pulling shots). Bigger shot volume helps a lot in building stronger latte if that's your thing.

Randy G. wrote:17 grams in a Stock Rancilio double basket is a huge updose and could take a ball peen hammer tamper to get it all in there.

LOL, that would be the "Glass Blacksmith" move