eldeguello... it's a pneumatic rifle. The machinest rifles his own barrels and incorporates a twist rate acceptable to fire slugs that you might use to reload the .45-70 cartridge. The rifle will fire 510 grain slugs at about 700 fps or you can step down to roundball that will travel more than 1000 fps. I have started casting my own slugs from a Lyman 330 gr. hollowpoint mold.