Decreased Damage Level
From Nighthawks Shadowrun Wiki
Firearm Design Option (Cannon Companion)
By using a lighter ammunition round it is possible to free up space for further enhancements (often High velocity capability). This option decreases the damage level one level e.g. from M to L. It may be take on any weapon (except those with a damage category of L)
DP: +100
FCU: +1
Weight: +0.5
Concealability: None