Head to head

8mm Mauser vs .303 British: Maker-Page Loads and SAAMI Specs Side by Side

By Cole Harlan, EditorUpdated Nov 5, 2026How we verifyEditorial standards

This page puts 8mm Mauser and .303 British side by side using only our own ammo guides, 8mm Mauser ammo (3 loads) and .303 British ammo (5 loads), plus the cartridge specs SAAMI publishes in ANSI/SAAMI Z299.4, its centerfire rifle standard. The guides copy bullet weights, velocities, energies and test barrels from maker product pages (checked Nov. 5, 2026). We don’t rate or rank cartridges, and we don’t subtract one maker’s velocity from another’s, because their test barrels differ.

How to read this page: every number is copied from a maker page or from SAAMI, and a test barrel length sits next to every velocity (or says the maker lists none). A dash (—) means the maker has no load in our tables for that cartridge. Fire only the cartridge your rifle’s maker says it is chambered for.

Older rifles: our 8mm Mauser guide says to check any 8mm Mauser load against your rifle’s markings and a gunsmith before shooting it in an older military rifle. That caution is the guide’s, not a statement about any particular rifle.

SAAMI specs side by side

These are the figures in ANSI/SAAMI Z299.4 (approved Feb. 10, 2025), as already recorded in the SAAMI sections of our 8mm Mauser and .303 British guides. Pressures are as SAAMI lists them.

Measure	8mm Mauser	.303 British
SAAMI name	8MM MAUSER (8 X 57) [8MM (8 X 57)]	303 BRITISH [303 BRIT]
Drawing issued / revised	04/21/1980 / 03/02/2022	05/29/1979 / 02/10/2023
Maximum average pressure (transducer)	35,000 psi	49,000 psi
Crusher pressure	37,000 CUP	45,000 CUP
Cartridge overall length	2.815 in min to 3.250 in max	2.915 in min to 3.075 in max
Case length	2.240 in (−.020)	2.222 in (−.020)
Bullet diameter (as SAAMI prints it)	Not yet verified	Not yet verified
Bore / groove diameter	Not yet verified	Not yet verified
Twist and grooves	1 in 8.00, 4 grooves (marked optional)	1 in 10.00, 5 grooves (marked optional)
SAAMI reference velocity	Not yet verified (the PDF text does not clearly pair each weight with its velocity)	Not yet verified (the PDF text does not clearly pair each weight with its velocity)
SAAMI velocity test barrel	24 in standard rifle test barrel (SAAMI’s general statement; not among its listed exceptions)	24 in standard rifle test barrel (SAAMI’s general statement; not among its listed exceptions)

Load ranges by maker and test barrel

Each line groups one maker’s loads that share a test barrel, so a velocity is only ever shown with the barrel it was measured in. Ranges are bullet weight (where the guide table prints it) and muzzle velocity as the maker page prints them. Do not read across makers: their barrels and bullets differ. For how barrel length moves velocity, see our barrel length vs velocity data.

Maker	8mm Mauser loads in our table	.303 British loads in our table
Federal	test barrel not listed: 1 load, 170 gr, 2,250 fps	test barrel not listed: 2 loads, 150 to 180 gr, 2,460 to 2,690 fps
Hornady	test barrel printed as “24 cm” (unit not verified): 1 load, 195 gr SP Custom International™, 783 m/sec (as printed; not converted) 24 in test barrel: 1 load, 196 gr, 2,500 fps	24 in test barrel: 1 load, 150 gr, 2,685 fps
Remington	—	test barrel not listed: 2 loads, 174 to 180 gr, 2,460 to 2,475 fps

Same maker, same line, both cartridges

Where one maker sells the same product line in both cartridges, the loads are listed side by side exactly as the maker pages print them. We match lines by the maker’s own product-line name in our guide tables. Compare only within a row, and check the test barrel in each cell.

Maker line	8mm Mauser	.303 British
Federal Power-Shok Rifle	170 gr Jacketed Soft Point, 2,250 fps, 1,911 ft-lb, test barrel not listed, item 8A	150 gr Jacketed Soft Point, 2,690 fps, 2,410 ft-lb, test barrel not listed, item 303B 180 gr Jacketed Soft Point, 2,460 fps, 2,418 ft-lb, test barrel not listed, item 303AS

What the sources say when you choose

These are points taken from the figures above, each with the page it rests on. They are not recommendations or scores.

If pressure rating is your question: SAAMI lists a maximum average pressure of 35,000 psi (transducer) (crusher 37,000 CUP) for 8mm Mauser and 49,000 psi (transducer) (crusher 45,000 CUP) for .303 British. Source: ANSI/SAAMI Z299.4.
If bullet weight is your question: The 8mm Mauser loads in the table run from 170 gr to 196 gr; the .303 British loads in the table run from 150 gr to 180 gr. The ranges come from each guide’s own bullet-weight section. Source: 8mm Mauser guide and .303 British guide.
If you want to see the printed velocities: the slowest and fastest muzzle velocities in our table: for 8mm Mauser: 2,250 fps, test barrel not listed (Federal Power-Shok Rifle 8A) and 2,500 fps, 24 in test barrel (Hornady Vintage Match 82298). For .303 British they are 2,460 fps, test barrel not listed (Federal Power-Shok Rifle 303AS) and 2,690 fps, test barrel not listed (Federal Power-Shok Rifle 303B). These come from different barrels and bullets, so we show them side by side without subtracting.
If you are comparing against a box or a chronograph: SAAMI says all standard rifle test barrels are 24 in long. Many maker pages list a different barrel or none, as the tables above show. A shorter barrel than the one a maker lists will likely give lower velocities than the box; see our barrel length vs velocity data. Source: ANSI/SAAMI Z299.4 and the maker pages linked above.
If chamber fit is your question: SAAMI publishes a separate cartridge drawing for each: case length 2.240 in (−.020), cartridge overall length 2.815 in min to 3.250 in max for 8mm Mauser; and case length 2.222 in (−.020), cartridge overall length 2.915 in min to 3.075 in max for .303 British. Check the cartridge named in your rifle’s manual or marked on its barrel. Source: ANSI/SAAMI Z299.4.

Not yet verified

The 8mm Mauser guide has 3 loads and the .303 British guide has 5, so load counts and ranges are not a measure of how many loads exist; they only reflect what is in our tables. 8mm Mauser has the thinner table (3 loads); we state that plainly and draw no conclusion from it.
SAAMI bullet, bore and groove diameters for 8mm Mauser and .303 British are not verified in our guides (the PDF text does not pair each figure with its label clearly), so those rows are marked rather than filled.
Hornady’s 195 gr SP Custom International 8x57 JS page (item 82291) prints its ballistics in m/sec and joules, with a test barrel shown as “24” and “cm.” We copied it as printed, did not convert it, and left it out of the fps ranges. Maker cartridge labels differ (Hornady 8x57 JS, Federal 8mm Mauser), so confirm which one your rifle is marked for.
Makers not shown in a column are not in that guide’s table (see the “Not yet verified” section of each guide), so a dash means no load in our table, not that the maker sells none.
Prices, recoil, accuracy and hands-on results are not in our data, so this page says nothing about them.

See the full tables in our 8mm Mauser ammo and .303 British ammo, plus .30-06 ammo, .308 Win ammo, 7.62x39 ammo, .30-30 ammo, .270 Win ammo, .308 Win vs .30-06, the SAAMI maximum average pressure table, the barrel length vs velocity data, the new ammo of 2026, all ammo releases, all comparisons.

Frequently asked questions

What is the SAAMI maximum pressure for 8mm Mauser and .303 British?

SAAMI lists 35,000 psi (transducer) (crusher 37,000 CUP) for 8mm Mauser and 49,000 psi (transducer) (crusher 45,000 CUP) for .303 British, in ANSI/SAAMI Z299.4.

Which test barrel do the makers list?

It varies by maker and load. SAAMI says standard rifle test barrels are 24 in. Our tables show the barrel each maker page lists next to every velocity, and many pages list none.

Which is better, 8mm Mauser or .303 British?

We don't rate or rank cartridges. This page copies maker-page figures and SAAMI specs side by side, and it does not cover price, recoil or hands-on results.

Where do these numbers come from?

From our own ammo guides (8mm Mauser ammo and .303 British ammo), which copy maker product pages, and from ANSI/SAAMI Z299.4.

8mm Mauser vs .303 British: Maker-Page Loads and SAAMI Specs Side by Side

SAAMI specs side by side

Load ranges by maker and test barrel

Same maker, same line, both cartridges

What the sources say when you choose

Not yet verified

Frequently asked questions

Sources

Keep exploring

SAAMI specs side by side

Load ranges by maker and test barrel

Same maker, same line, both cartridges

What the sources say when you choose

Not yet verified

Related guides

Frequently asked questions

Sources

Keep exploring

The Gun Release Report