.30-378 Weatherby Magnum

.30-378 Weatherby Magnum
Type	Rifle
Place of origin	USA
Production history
Designer	Weatherby
Designed	1959 by request of US Army for long range rifle.
Manufacturer	Weatherby
Produced	1996 - Current
Variants	.30-.378 Magnum, .30/378 Arch, .30/378 Weatherby
Specifications
Parent case	.378 Weatherby Magnum
Bullet diameter	.308 in (Bad rounding here mm)
Neck diameter	.337 in (Bad rounding here mm)
Shoulder diameter	.561 in (Bad rounding here mm)
Base diameter	.582 in (Bad rounding here mm)
Rim diameter	.579 in (Bad rounding here mm)
Case length	2.913 in (Bad rounding here mm)
Overall length	3.690 in (Bad rounding here mm)
Rifling twist	1-10"
Primer type	Large rifle magnum
Maximum pressure	63,817 psi (Bad rounding here MPa)
Ballistic performance
Bullet weight/type	Velocity	Energy
165 gr (Bad rounding here g) BST	3,500 ft/s (Bad rounding here m/s)	4,488 ft·lbf (Bad rounding here J)
180 gr (Bad rounding here g) BST	3,420 ft/s (Bad rounding here m/s)	4,676 ft·lbf (Bad rounding here J)
200 gr (Bad rounding here g) Partition	3,160 ft/s (Bad rounding here m/s)	4,434 ft·lbf (Bad rounding here J)
Test barrel length: 26" (660 mm) Source(s): Weatherby

The .30-378 Weatherby Magnum is a cartridge introduced by Weatherby in 1996 that uses the same case as the previously existing .378 Weatherby Magnum and .460 Weatherby Magnum, necked down to a 30 caliber (7.62 mm) bullet. It is offered with bullets between 165 and 200 grains (10.7 g and 13.0 g) in factory loading, generating velocities able to exceed 3,500 ft/s (Bad rounding here m/s) and muzzle energies over 4,750 foot-pounds force (Bad rounding here J). The cartridge was the product of a design/development effort of 1958-1959 between Mr William L. Strickland at the U S Army Ballistics Laboratory of Redstone Arsenal Alabama and Roy Weatherby. The research development contract specified the development/production of a single shot rifle/cartridge combination which could provide a flat nosed and based, 80gr and 100 gr projectile velocity of 6000 ft/s. 35mm high speed motion picture cameras were used to photograph the performance and impact results of various projectile alloys while impacting different types of armor plate. The rifle was removed from the stock and mounted in a machine rest, the armor plate targets were 10' in front of the muzzle. The results of this testing have helped the Army in the development of effective battlefield armor and armor penetrators used on the battlefield today. In later years, projectiles fired in this rifle were studied and designed for hunting game at very long distances, and for marksmanship competition in excess of 1,000 yards (Bad rounding here m). ^{[citation needed]}

Performance

The .30-378 case holds as much as 120 grains ( g) of powder without requiring a compressed load. This allows the cartridge to develop more energy than the .300 Remington Ultra Magnum and .300 Winchester Magnum, especially when handloads are used.

Muzzle Energy Comparison

Cartridge	Bullet Weight		Muzzle velocity		Muzzle energy		Notes
	gr	g	ft/s	m/s	ft·lbf	J
.458 Win Mag	500	Bad rounding here	2,240	Bad rounding here	5,570	Bad rounding here	Winchester Safari Supreme loading
.338 Lapua	300	Bad rounding here	2,800	Bad rounding here	5,224	Bad rounding here	Black Hills Ammo loading
.375 H&H	300	Bad rounding here	2,705	Bad rounding here	4,875	Bad rounding here	Hornady Heavy Magnum loading
.30-378 Wby	200	Bad rounding here	3,160	Bad rounding here	4,434	Bad rounding here	Weatherby factory load
.300 RUM	200	Bad rounding here	3,100	Bad rounding here	4,269	Bad rounding here	Loading from Nosler custom
.300 Win Mag	180	Bad rounding here	3,050	Bad rounding here	3,720	Bad rounding here	Reference load by Doubletapammo

Note: Using the bullet weight and muzzle velocity in each cartridge that provided the maximum muzzle energy. Data for the .30-378 is from. Loading data for all other cartridges can be found at

Performance at ¼ mile (440 yd or 402.3 m)

Cartridge	Weight		Ballistic Coefficient	Muzzle Velocity		Muzzle Energy		Velocity at 440 yd (Bad rounding here m)		Energy at 440 yd (Bad rounding here m)
	gr	g		ft/s	m/s	ft·lbf	J	ft/s	m/s	ft·lbf	J
.30-06	165		0.475	2,938	Bad rounding here	3,165	Bad rounding here	2,110	Bad rounding here	1,633	Bad rounding here
.30-378	165		0.475	3,500	Bad rounding here	4,448	Bad rounding here	2,576	Bad rounding here	2,428	Bad rounding here
.30-06	180		0.507	2,798	Bad rounding here	3,130	Bad rounding here	2,044	Bad rounding here	1,668	Bad rounding here
.30-378	180		0.507	3,420	Bad rounding here	4,676	Bad rounding here	2,559	Bad rounding here	2,619	Bad rounding here
.30-06	200		0.481	2,586	Bad rounding here	2,972	Bad rounding here	1,841	Bad rounding here	1,502	Bad rounding here
.30-378	200		0.481	3,160	Bad rounding here	4,434	Bad rounding here	2,300	Bad rounding here	2,351	Bad rounding here

Note: data for the .30-378 from Weatherby (which tracks closely to what handloaders can achieve based on loading data at. Data from the .30-06 is also from Hodgdon. The initial data used is included here for anyone who cares to run the calculations themselves.

Costs

Rifles built by Weatherby are available in .30-378, and ammunition is significantly more expensive than other cartridges, with ammunition costing upwards of $120 USD for a box of 20 rounds as of 2012. Weatherby offers this caliber in several versions of its Mark V rifle. Due to the strong recoil a round of this energy can create, all Weatherby rifles offered in this caliber include a muzzle-brake. SAKO offered the TRG-S in .30-378 Weatherby at one time but now lists the TRG-S as an "Old Model" and is no longer available.

See also

• List of rifle cartridges
• 7 mm caliber

References

• Who Wins? The .30-378 Versus The 7 mm STW at Gun-Tests.com
• .30-378 Weatherby by Chuck Hawks
• The .300 Super Magnums by Chuck Hawks
• Cartridge Dimensions at Steve's Pages

External links

• Further reloading data at Hodgdon