If Nerf Hyper rounds are 13-14mm diameter, then it stands to reason that with minor modifications the Sportsman would be able to fire them. With a massive hopper it may make for
Turned my nerf hyper Mach 100 into a Kriss vector : r/nerfmods
Amazon.com: POKONBOY Upgraded 500-Round Balls Refill Pack Compatible with Nerf Rival Apollo, Zeus, Atlas and Artemis Blasters (Storage Bag Included) : Toys & Games
Nerf Gun
Amazon.com: NERF Rival Curve Shot -- Helix XXI-2000 Blaster -- Fire Rounds to Curve Left, Right, Downward or Fire Straight -- 20 Rival Rounds : Toys & Games
For no reason, here's my Hyper collection. Was really hyped about Hyper initially but passions have cooled considerably. More comments in post. : r/ Nerf