20rds 50 AE Underwood 300gr. FMJ Ammo For Sale. The FMJ bullet has a unique design with a flat tip, which causes more damage to soft tissue upon penetration. The FMJ FN bullet’s inability to expand has the extra advantage of greater penetration, so even animals with thick hide and solid muscle are no match for the powerful 50 AE. In Sparta, Illinois, Underwood loads its superior pistol rounds with select reloadable brass casings and sensitive primers. The formulation of Underwood’s renowned flash-suppressed powder produces a muzzle flash that is less bright than typical. This will preserve your night vision so you can continue to shoot accurately!