Description
Roy Weatherby necked the 378 case down to 30 caliber in 1959 at the Army request, and the result has been overbore, loud and devastating ever since. The Weatherby 30-378 WBY 180gr Scirocco II is the modern version of that idea: a bonded bullet built to survive arriving at 3275 feet per second.
- Why the 30-378 Needs a Bonded Bullet
- Weatherby 30-378 WBY 180gr Scirocco II Specifications
- Honest Notes on Living With a 30-378
Why the 30-378 Needs a Bonded Bullet
Impact velocity is what destroys hunting bullets, and the 30-378 generates more of it than almost any other 30 caliber cartridge. A conventional cup-and-core bullet arriving inside 200 yards at well over 3000 feet per second tends to come apart on the near shoulder, leaving a spectacular surface wound and an animal that walks away. That failure mode is precisely why Weatherby pairs this cartridge with the Swift Scirocco II.
The Scirocco II uses a bonded core, meaning the lead is chemically fused to the jacket rather than merely pressed into it. The bullet expands to roughly twice its diameter and then stops, holding somewhere around 70 to 80 percent of its original weight even at brutal close-range velocities. Combined with a thick 0.030 inch jacket base and a polymer tip, it behaves the same way at 50 yards and at 500.
The Weatherby 30-378 WBY 180gr Scirocco II is loaded in Sheridan, Wyoming, as part of the Select Plus line, which is Weatherby premium factory ammunition rather than its value tier.
Weatherby 30-378 WBY 180gr Scirocco II Specifications
The published numbers are 3275 feet per second and roughly 4287 foot-pounds at the muzzle, with a G1 ballistic coefficient of 0.520. For context, that is more muzzle energy than a 375 H and H with a 300 grain load, delivered with a trajectory flat enough that a 300 yard zero keeps you inside vital-zone holds well past 400.
That performance is bought with powder. A 30-378 case swallows well over 100 grains of slow-burning propellant, and the practical consequences are real: significant muzzle blast, meaningful recoil in anything under nine pounds scoped, and barrel life that most owners measure in the low hundreds of rounds rather than thousands. None of that is a defect, it is simply the cost of the velocity.
Cases are reloadable boxer-primed brass, which matters more than usual here. Factory 30-378 ammunition is expensive, and hunters who shoot it regularly almost always end up reloading the once-fired brass from boxes like this one.
- Cartridge: 30-378 Weatherby Magnum
- Bullet weight: 180 grain
- Bullet type: Swift Scirocco II bonded polymer tip boat tail
- Muzzle velocity: 3275 feet per second
- Muzzle energy: approximately 4287 foot-pounds
- G1 ballistic coefficient: 0.520
- Sectional density: 0.271
- Case: brass, boxer primed, reloadable
- Series: Weatherby Select Plus
- Rounds per box: 20
- Manufacturer part number: F303180SCO
- UPC: 747115452019
Honest Notes on Living With a 30-378
Buy the Weatherby 30-378 WBY 180gr Scirocco II if you own a 30-378 and hunt elk, moose, or big bears at distances where a lesser cartridge would run out of energy. This is the load that justifies owning the chambering in the first place.
Skip it for deer inside 200 yards. It works, but you will waste a lot of barrel life and a lot of money on an animal a 30-06 handles comfortably, and the meat damage from a close-range magnum impact is not trivial even with a bonded bullet.
Skip it if your rifle wears a muzzle brake and you shoot without hearing protection. A braked 30-378 is genuinely dangerous to unprotected ears, and that is worth saying plainly rather than burying in a footnote.
Feeding a Mark V? The Weatherby Mark V Accumark 28 inch 30-378 is the rifle this load was built around, and Weatherby 30-378 unprimed brass is available if you reload. Swift publishes full Scirocco II bullet data on its own site.
MAG5 Firearms stocks Weatherby Select Plus ammunition and the Mark V rifles chambered for it. Ask about case pricing if you shoot enough 30-378 to make it worthwhile.
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