I believe the inside diameter of an Axis is .204,which would be closer to a 20 caliber.You have your 22 caliber guns which would be .223 diameter,alittle large.Their is a Sheridan pellet rifle which shoots a 20 caliber(5mm) pellet that may be a closer fit.You may find a brass rod at a hardware store you can cut and fit them inside to add weight.There is always the 100 gr. brass inserts,but any weight you add to the front end will change the tune of the arrow.A 243 bullet will work inside GT's,Vapors and ICS Beman,but would be to large for the Axis shaft.