The 30-378 Weatherby Magnum is not listed in SAAMI’s rifle (Z299.4), handgun (Z299.3) or rimfire (Z299.1) standards, so there is no SAAMI reference velocity, pressure limit or test barrel to quote for it. This guide charts what the makers of the loads we stock publish for them instead, and compares the 30-378 Weatherby Magnum with the 300 Weatherby Magnum, which SAAMI does standardise.
30-378 Weatherby Magnum ballistics chart: manufacturer-published loads
These are the manufacturers’ own figures for specific loads we stock, taken from each maker’s page for the item number shown. There is no SAAMI reference for this cartridge, and each maker chose its own test barrel, so the figures should not be laid directly beside another brand’s.
Scroll the table sideways for the remaining columns.
| Load | Item no. | Bullet weight | Bullet | Muzzle velocity | Muzzle energy | Test barrel |
|---|---|---|---|---|---|---|
| HSM Ammunition Berger VLD Match Hunting | 30378185VLD | 185 gr | Berger VLD Match Hunting | 3,334 fps | 4,567 ft-lb | Not published |
| HSM Ammunition Berger VLD Match Hunting | 30378210VLD | 210 gr | Berger VLD Match Hunting | 3,170 fps | 4,687 ft-lb | Not published |
What the numbers mean for a shot
The 2 loads charted above, from HSM Ammunition, run from 185 to 210 grains, with published muzzle velocities of 3,170 to 3,334 fps and published muzzle energies of 4,567 to 4,687 ft-lb. Each maker fired its load in its own test barrel, so a difference between two brands can come from the barrel as well as the load.
None of this is SAAMI data. Each product in our 30-378 Weatherby Magnum ammo range lists whatever its maker publishes for that item.
Chamber and pressure
This page states no SAAMI pressure limit for the 30-378 Weatherby Magnum. Fire 30-378 Weatherby Magnum ammunition only in a firearm chambered for it, and follow both the ammunition maker’s and the firearm maker’s instructions. Several unrelated cartridges share a number, so match the full designation on the box to the marking on your barrel.
30-378 Weatherby Magnum vs 300 Weatherby Magnum: what the data supports
A like-for-like comparison needs both cartridges measured the same way. SAAMI standardises the 300 Weatherby Magnum, so its figures come from one standard test barrel. The 30-378 Weatherby Magnum has no SAAMI figures, so its numbers come from individual makers and their own barrels. The table sets them side by side with the source of each figure stated, and should be read that way.
Scroll the table sideways for the remaining columns.
| Specification | 30-378 Weatherby Magnum | 300 Weatherby Magnum |
|---|---|---|
| Listed by SAAMI | No | Yes |
| Maximum average pressure | Not published by SAAMI | 65,000 psi (SAAMI) |
| Bullet weights | 185 to 210 gr (loads we stock) | 165 to 220 gr (SAAMI reference loads) |
| Muzzle velocity | 3,170–3,334 fps (manufacturer-published, each in its own barrel) | 2,775–3,140 fps (SAAMI reference, 24.000 in test barrel) |
| Muzzle energy | 4,567–4,687 ft-lb (where the maker publishes it) | 3,612–3,902 ft-lb (computed from SAAMI velocity) |
What this cannot settle is which cartridge is more powerful in your rifle: the two columns come from different sources and different barrels. We stock the other side of this comparison too: 300 Weatherby Magnum ammo.
30-378 Weatherby Magnum ballistics questions
Does SAAMI standardise the 30-378 Weatherby Magnum?
No. SAAMI’s rifle, handgun and rimfire standards do not list the 30-378 Weatherby Magnum, so there is no SAAMI maximum pressure, reference velocity or test barrel for it. The figures on this page are the ones each maker publishes for its own loads.
What muzzle velocity do manufacturers publish for the 30-378 Weatherby Magnum?
For the 2 loads we stock from HSM Ammunition, the makers publish muzzle velocities from 3,170 to 3,334 fps, for bullet weights from 185 to 210 grains. Each maker measured its own load in its own test barrel, so these are not reference figures and are not directly comparable between brands.
Is the 30-378 Weatherby Magnum more powerful than the 300 Weatherby Magnum?
The two cannot be compared like for like, because SAAMI publishes reference data for the 300 Weatherby Magnum but not for the 30-378 Weatherby Magnum. The 2 loads charted here for the 30-378 Weatherby Magnum publish muzzle energies of 4,567 to 4,687 ft-lb, each in its maker’s own barrel, against SAAMI reference loads for the 300 Weatherby Magnum that compute to 3,612 to 3,902 ft-lb from a 24.000 in test barrel.
What is the effective range of the 30-378 Weatherby Magnum?
Effective range is not a published specification for the cartridge; it depends on the bullet, the load and the shooter. Where a maker publishes downrange velocity and energy for a load, the tables above show it, and only out to the last range that maker publishes.
How much does the 30-378 Weatherby Magnum drop?
None of the makers of the loads we stock publishes a trajectory table for them, so this page gives no drop figure. Drop depends on the bullet’s ballistic coefficient and on the zero range, so use the figure a maker prints for the specific load.
Where to buy these loads
Hilltop Armory carries 30-378 Weatherby Magnum ammunition from Nosler, Hornady, HSM Ammunition and Norma. Browse the full 30-378 Weatherby Magnum ammo range.
