The in-game UI considers any possible multishot capabilities when showing final damage numbers, and will display the damage of the weapon as if it was fired once.
Example: A Braton with a level 4 Split Chamber (75%) showing 36 of the total damage, with a 25% chance that the Braton will show a total damage of 18.
This mod also has an effect on weapons with 100% accuracy (such as the Dera), but since the projectiles do not spread out, the extra projectile is generated inside the original projectile. This mod's effects are much more noticeable if Heavy Caliber is installed, as the accuracy penalty generated will allow the projectiles to noticeably spread.
When calculating DPS for weapons using this mod, apply the damage bonus caused by this mod as a separate multiplier after all other factors have been accounted for.
Arsenal shows a bonus to status chance when using Split Chamber that is equal to the chance of firing a bonus round.