The 7.8x74mm Magnum cartridge has been in use by the Nepleslian Space Marine Corps and Nepleslia as a whole for as long as most can remember, it is a time-tested design used by hunters military and civilian alike and is commercially available in 120 to 200 grain loads as needed.
While hand-loaded variants are available through those with the equipment and/or know-how the standard design is a cupronickel-jacketed lead slug with a penetrating steel core and a red polymer tip loaded inside a brass casing, though steel-cased variants can be found commonly enough and for lower prices.
The hardened polymer tip ensures superior and more consistent flight-path though still allows vicious expansion of the bullet once it hits, tracer variants exist and are mostly used to ignite flammable substances or draw attention towards targets.