The 500 Auto Max 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 500 Auto Max with the 50 Action Express, which SAAMI does standardise.
500 Auto Max 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 | Ballistic coefficient | Test barrel |
|---|---|---|---|---|---|---|---|
| Underwood eXtreme Terminal Performance (XTP®) Jacketed Hollow Point | Not published | 350 gr | eXtreme Terminal Performance (XTP®) Jacketed Hollow Point | 2,300 fps | 4,112 ft-lb | 0.145 G1 | Not published |
| Underwood Xtreme Penetrator® Solid Monolithic | Not published | 350 gr | Xtreme Penetrator® Solid Monolithic | 2,200 fps | 3,762 ft-lb | 0.235 G1 | Not published |
What the numbers mean for a shot
The 2 loads charted above, from Underwood, run from 350 to 350 grains, with published muzzle velocities of 2,200 to 2,300 fps and published muzzle energies of 3,762 to 4,112 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 500 Auto Max ammo range lists whatever its maker publishes for that item.
Chamber and pressure
This page states no SAAMI pressure limit for the 500 Auto Max. Fire 500 Auto Max 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.
500 Auto Max vs 50 AE: what the data supports
A like-for-like comparison needs both cartridges measured the same way. SAAMI standardises the 50 Action Express, so its figures come from one standard test barrel. The 500 Auto Max 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 | 500 Auto Max | 50 Action Express |
|---|---|---|
| Listed by SAAMI | No | Yes |
| Maximum average pressure | Not published by SAAMI | 35,000 psi (SAAMI) |
| Bullet weights | 350 to 350 gr (loads we stock) | 300 to 325 gr (SAAMI reference loads) |
| Muzzle velocity | 2,200–2,300 fps (manufacturer-published, each in its own barrel) | 1,400–1,550 fps (SAAMI reference, 6.000 in test barrel) |
| Muzzle energy | 3,762–4,112 ft-lb (where the maker publishes it) | 1,414–1,600 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: 50 AE ammo.
500 Auto Max ballistics questions
Does SAAMI standardise the 500 Auto Max?
No. SAAMI’s rifle, handgun and rimfire standards do not list the 500 Auto Max, 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 500 Auto Max?
For the 2 loads we stock from Underwood, the makers publish muzzle velocities from 2,200 to 2,300 fps, for bullet weights from 350 to 350 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 500 Auto Max more powerful than the 50 Action Express?
The two cannot be compared like for like, because SAAMI publishes reference data for the 50 Action Express but not for the 500 Auto Max. The 2 loads charted here for the 500 Auto Max publish muzzle energies of 3,762 to 4,112 ft-lb, each in its maker’s own barrel, against SAAMI reference loads for the 50 Action Express that compute to 1,414 to 1,600 ft-lb from a 6.000 in test barrel.
What is the effective range of the 500 Auto Max?
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 500 Auto Max 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 500 Auto Max ammunition from Steinel Ammunition Co. and Underwood. Browse the full 500 Auto Max ammo range.
