R-Hop

Rather than relying only on the bucking's nub for spin, an R-Hop adds a curved strip — often a section cut from a second bucking or a purpose-made insert — glued along the top of the barrel just past the hop chamber, so the BB stays in gentle contact with a spinning surface for a longer stretch of its travel.

Properly installed, an R-Hop is widely regarded as the ceiling for range and grouping a hop-up unit can achieve, but the DIY installation is fiddly — precise trimming and gluing — and a poorly done one performs worse than a stock setup, which is why it has a reputation as an advanced, not beginner, upgrade.

A poorly seated R-Hop strip can actually chop BBs or cause severe curving, so most guides recommend practicing the trim-and-glue process on a cheap spare barrel section before committing to a barrel that's already installed in a working gun.