Maybe I’m just late to the party and don’t know about an impact mk4 ?
www.dlhdev.com
STUD Magazine for - FX Impact MK2,3,4 | Stud Mag Loaders
Fits: FX Impact .177, .22, .25, .30 or .35 caliber versions, will feed pellets or slugs up to 12mm (.472") in length. If using pellets in the magazine, do not use any type of "pin style" probe with a reduced front diameter. Damage to the pellet skirts will occur as the mag cycles. Any type of...
www.dlhdev.com 
