The 2006 and later SSS fork that's still being used bottoms against oil. If there is no oil, it bottoms metal to metal. No bumpers. Cast into the bottom of each axle lug (the part the inner tube screws into) is a cylindrical extension about 1.5 -2" tall, centered right down the tube axis, and with a machined bore that is only a small amount larger than the oil lock collars on the ends of the cartridges. The oil locks are those aluminum collars at the bottom of the cartridge, held on by thin retaining rings. They can be replaced and resized for either tuning or repairs, BTW.
As the fork compresses, the cartridge runs deeper into the outer chamber oil, displacing it around the nose of the damper. When the cartridge nose is driven into the last 1.5" (more or less) of travel, it enters the oil lock cylinder and suddenly has to move oil out of the way through a much tighter clearance gap. Most of the locks have tapered noses to soften the impact, and the shape can vary (or be varied). When it's set up correctly as to clearance and oil weight, the metal parts never come into contact, because the fork rebounds before the oil has time to be completely emptied from the oil lock.
All of that effectively turns the end of the cartridge, including the seal, into a piston crown. The pressure that results can be extremely high for a moment.