The 405 Winchester is a centerfire rifle cartridge standardised by SAAMI in ANSI/SAAMI Z299.4. SAAMI sets its maximum average pressure at 46,000 psi, and measures its reference velocities in a 24.000 in standard test barrel rifled 1 turn in 14.00 in. This guide sets out SAAMI’s published reference velocity for each bullet weight, computes the muzzle energy each one carries, and compares the 405 Winchester with the 45-70 Government on the same basis.
405 Winchester ballistics chart: SAAMI reference data
SAAMI publishes one nominal mean instrumental velocity for each reference bullet weight, measured at 15 feet from the standard test barrel. It does not publish energy, so the ft-lb column is computed. Where SAAMI lists more than one velocity for a weight, both ends of the span are shown.
Scroll the table sideways for the remaining columns.
| Bullet weight | Reference velocity | Computed muzzle energy |
|---|---|---|
| 300 gr | 2,200 fps | 3,224 ft-lb |
What the numbers mean for a shot
SAAMI lists a single reference bullet weight for the 405 Winchester: 300 grains, listed at 2,200 fps, which computes to 3,224 ft-lb. SAAMI publishes no other weight for it, so the table has one row. For any other bullet weight, use the figures the maker publishes for that item.
None of this is a downrange figure. SAAMI measures at 15 feet, so retained velocity, energy and drop depend on the bullet’s ballistic coefficient, which SAAMI does not publish. Each product in our 405 Winchester ammo range lists whatever its maker publishes for that item.
Twist rate, chamber and pressure
SAAMI’s standard test barrel for the 405 Winchester is 24.000 in long and rifled 1 turn in 14.00 in, with a .412 in groove diameter. That is the barrel every reference velocity above was measured in, not a statement about your rifle: a shorter production barrel will usually give lower velocity, and a twist slower than a bullet needs will not stabilise it. The maximum average pressure is 46,000 psi. Fire 405 Winchester ammunition only in a firearm chambered for it. Several unrelated cartridges share a number, so match the full designation on the box to the marking on your barrel.
405 Winchester vs 45-70: the SAAMI comparison
A figure from one maker’s catalogue cannot be laid beside a figure from another’s: each picks its own test barrel, zero and bullet, and many publish no test barrel at all. SAAMI is the shared basis, because it fixes one standard test barrel and one way of measuring velocity for every cartridge it lists.
Scroll the table sideways for the remaining columns.
| SAAMI specification | 405 Winchester | 45-70 Government |
|---|---|---|
| Maximum average pressure | 46,000 psi | 28,000 psi |
| Standard test barrel length | 24.000 in | 24.000 in |
| Test barrel twist rate | 1 turn in 14.00 in | 1 turn in 20.00 in |
| Test barrel groove diameter | .412 in | .456 in |
| Lightest reference load | 300 gr — 2,200 fps / 3,224 ft-lb | 250 gr — 2,025 fps / 2,276 ft-lb |
| A weight both list | 300 gr — 2,200 fps / 3,224 ft-lb | 300 gr — 1,830–1,880 fps / 2,230–2,354 ft-lb |
| Heaviest reference load | 300 gr — 2,200 fps / 3,224 ft-lb | 405 gr — 1,150–1,600 fps / 1,189–2,302 ft-lb |
SAAMI standardises the 405 Winchester at 46,000 psi and the 45-70 Government at 28,000 psi, so the 405 Winchester runs 18,000 psi higher. At 300 grains, a weight both list, SAAMI’s 405 Winchester reference velocity is 2,200 fps (3,224 ft-lb computed), against up to 1,880 fps (2,354 ft-lb) for the 45-70 Government. On that row the 405 Winchester carries the more energy. Their standard test barrels differ (24.000 in, 1 turn in 14.00 in for the 405 Winchester; 24.000 in, 1 turn in 20.00 in for the 45-70 Government), so compare the reference rows with that in mind.
What SAAMI cannot settle is anything past the muzzle. It publishes no ballistic coefficients and no downrange data, so it cannot say which cartridge shoots flatter at distance; that depends on the bullet. We stock the other side of this comparison too: 45-70 ammo.
405 Winchester ballistics questions
What is the maximum pressure of the 405 Winchester?
ANSI/SAAMI Z299.4 sets the maximum average pressure for the 405 Winchester at 46,000 psi.
What twist rate and barrel length does SAAMI use for the 405 Winchester?
SAAMI’s standard test barrel for the 405 Winchester is 24.000 in long and rifled 1 turn in 14.00 in. Your own rifle may differ.
Is the 405 Winchester more powerful than the 45-70 Government?
Power is not a SAAMI measure, but reference muzzle energy is a fair proxy. At 300 grains, a weight both list, SAAMI’s 405 Winchester reference velocity is 2,200 fps (3,224 ft-lb computed), against up to 1,880 fps (2,354 ft-lb) for the 45-70 Government.
What is the effective range of the 405 Winchester?
Effective range is not a SAAMI specification and it is not a measured figure. SAAMI measures velocity at 15 feet, so it says nothing about performance at distance; that depends on the bullet and the shooter.
How much does the 405 Winchester drop at 300 yards?
SAAMI publishes muzzle velocity only, so it cannot give a drop figure. Drop depends on the bullet’s ballistic coefficient and on the zero range. A drop figure is unusable without its zero, so use the figure a maker prints for the specific load.
Where to buy these loads
Hilltop Armory carries 405 Winchester ammunition from Hornady, Kynoch and Winchester. Browse the full 405 Winchester ammo range.
