This is a drop-in part that enables the fate to fire mega and mega xl darts accurately with no permanent modification. That said, in order for mega xl to fire when fully seated, you will at minimum need to improve the air seal of the plunger tube and system as a whole. The stock spring should get you around 75 fps with mega and 45 fps with MXL, but a spring upgrade is recommended for greater performance and reliability when firing MXL.
The author remixed this model.
This model utilizes the profile of Ellie's MXL fate barrel and adds the rifling and tolerances from Silly's Mega and MXL silly shells to fire those dart types with improved performance and precision.