Hi Julian, this is a .177 caliber lever action air rifle that takes Detachable S/Roto Index 14 shot magazine.
Not semi-auto, lever action.
Full details here >>> https://tacticalsurplususa.com/airgun-rifles/hatsan-vectis-177-caliber-airgun-1250fps-synthetic-black-stock/
Stay safe & have a great day!

it a 0.177 caliber air rifle pellets here budsgunshop.com/product_info.php/products_id/39036/crosman+copperhead+pellets+.177+steel

Hi Julian and welcome. This is a "Lever Action" .177 Caliber "Pellet" Air Rifle and has a 14-shot rotary magazine.
Vectis Specifications
.177 caliber lever-action repeating PCP air rifle
Up to 1250 FPS velocity
Up to 29 Ft-lbs energy
Rugged ambidextrous synthetic stock with hand guard cocking lever
Quattro 2-stage fully adjustable match trigger
QuietEnergy barrel technology reduces downrange noise output
17.7" barrel / 41.3" overall length / 7.1 lbs Thank you for checking out the Hatsan Vectis .177 Cal Air --- Cheers, stay safe and happy holidays!