Brenneke Magnum 20 Gauge 1 oz 3in Centerfire Shotgun Ammo 5 Rounds. It's one of the heaviest 20 GA slugs on the market giving you deep penetration even on longer distances. Comes with built in superb knock down power. Specifications for Brenneke Magnum 20 Gauge 1 oz 3" Shotgun Ammunition: Manufacturer: Brenneke Gauge: 20 Number of Rounds: 5 Shot Size: Slug Shell Length: 3 in Muzzle Velocity: 1476 ft/s Application: Hunting Included Accessories: None Shotgun Shot Weight: 1 oz Primer Style: Centerfire What is Brenneke Magnum 20 Gauge 1 oz 3" Shotgun Ammunition good for? The manufacturer suggests that it is good for hunting.Brenneke SL203M: Magnum 20 Gauge 1 oz 3in Centerfire Shotgun Ammo 5 Rounds