Head to head

.338 Lapua Mag vs .300 Win Mag: Maker-Page Loads and SAAMI Specs Side by Side

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

This page puts .338 Lapua Mag and .300 Win Mag side by side using only our own ammo guides, .338 Lapua Mag ammo (12 loads) and .300 Win Mag ammo (35 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. 4, 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.

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 .338 Lapua Mag and .300 Win Mag guides. Pressures are as SAAMI lists them.

Measure	.338 Lapua Mag	.300 Win Mag
SAAMI name	338 LAPUA MAGNUM [338 LAPUA MAG]	300 WINCHESTER MAGNUM [300 WIN MAG]
Drawing issued / revised	01/14/2013 / 03/08/2022	04/21/1980 / 05/31/2022
Maximum average pressure (transducer)	65,000 psi	64,000 psi
Crusher pressure	Not established	54,000 CUP
Cartridge overall length	3.5610 in min to 3.6811 in max	3.215 in min to 3.340 in max
Case length	2.7244 in (−.0201)	2.620 in (−.020)
Bullet diameter (as SAAMI prints it)	.3390 in (−.003)	.309 in (−.003)
Bore / groove diameter	.330 in / .338 in	.300 in / .308 in
Twist and grooves	1 in 10, 6 grooves	1 in 10, 6 grooves
SAAMI reference velocity	Not yet verified (the PDF text does not clearly pair each weight with its velocity)	Not in our .300 Win Mag guide
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 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	.338 Lapua Mag loads in our table	.300 Win Mag loads in our table
Federal	test barrel not listed: 2 loads, 250 to 300 gr, 2,580 to 2,950 fps	test barrel not listed: 18 loads, 150 to 200 gr, 2,810 to 3,150 fps
Hornady	24 in test barrel: 3 loads, 250 to 285 gr, 2,745 to 2,860 fps	24 in test barrel: 9 loads, 150 to 200 gr, 2,860 to 3,275 fps 26 in test barrel: 1 load, 178 gr, 2,960 fps
Nosler	24 in test barrel: 2 loads, 300 gr, 2,650 fps	—
Berger	26 in test barrel: 5 loads, 250 to 300 gr, 2,710 to 3,005 fps	—
Remington	—	test barrel not listed: 7 loads, 150 to 190 gr, 2,850 to 3,290 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	.338 Lapua Mag	.300 Win Mag
Federal Gold Medal Sierra MatchKing	250 gr Sierra Matchking Boat-Tail Hollow Point, 2,950 fps, 4,830 ft-lb, test barrel not listed, item GM338LM 300 gr Sierra Matchking Boat-Tail Hollow Point, 2,580 fps, 4,434 ft-lb, test barrel not listed, item GM338LM2	190 gr Sierra Matchking Boat-Tail Hollow Point, 2,900 fps, 3,548 ft-lb, test barrel not listed, item GM300WM
Hornady Match	250 gr BTHP Match™, 2,860 fps, 4,540 ft-lb, 24 in test barrel, item 8230 285 gr ELD® Match, 2,745 fps, 4,768 ft-lb, 24 in test barrel, item 82300	195 gr ELD® Match, 2,930 fps, 3,717 ft-lb, 24 in test barrel, item 82180 178 gr ELD® Match, 2,960 fps, 3,463 ft-lb, 24 in test barrel, item 82043
Hornady Precision Hunter	270 gr ELD-X® Precision Hunter®, 2,800 fps, 4,699 ft-lb, 24 in test barrel, item 82313	200 gr ELD-X® Precision Hunter®, 2,860 fps, 3,632 ft-lb, 24 in test barrel, item 82002 178 gr ELD-X® Precision Hunter®, 2,960 fps, 3,463 ft-lb, 26 in test barrel, item 82041

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 65,000 psi by transducer for .338 Lapua Mag and 64,000 psi by transducer (plus 54,000 CUP by crusher) for .300 Win Mag, with no crusher pressure established where none is shown. Source: ANSI/SAAMI Z299.4.
If bullet weight is your question: the .338 Lapua Mag loads in our table run from 250 gr (Federal Gold Medal Sierra MatchKing GM338LM) to 300 gr (Federal Gold Medal Sierra MatchKing GM338LM2). The .300 Win Mag loads run from 150 gr (Federal Power-Shok Rifle 300WGS) to 200 gr (Federal ELD-X P300WELDX1). Sources: those maker pages.
If you want to see the printed velocities: the slowest and fastest .338 Lapua Mag muzzle velocities in our table are 2,580 fps, test barrel not listed (Federal Gold Medal Sierra MatchKing GM338LM2) and 3,005 fps, 26 in test barrel (Berger Elite Hunter 81060). For .300 Win Mag they are 2,810 fps, test barrel not listed (Federal Terminal Ascent P300WTA1) and 3,290 fps, test barrel not listed (Remington Core-Lokt 29495). 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, and neither cartridge is on its list of exceptions. 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, with case length 2.7244 in (−.0201) for .338 Lapua Mag and 2.620 in (−.020) for .300 Win Mag, and cartridge overall length 3.5610 in min to 3.6811 in max and 3.215 in min to 3.340 in max. Check the cartridge named in your rifle’s manual or marked on its barrel. Source: ANSI/SAAMI Z299.4.

Not yet verified

3 Berger .338 Lapua Mag loads (Elite Hunter 81060 and Lapua Scenar 81122 and 81132) carry a “Discontinued” badge or title on the maker page, and those pages list only the specification-list muzzle figures; see the .338 Lapua guide for the details. We kept them in the counts and ranges above.
SAAMI reference velocities are not recorded for either cartridge in our guides.
A dash in the range table means the maker has no load in that guide’s 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 .338 Lapua Mag ammo and .300 Win Mag ammo, the barrel length vs velocity data, .300 Win Mag barrel length vs velocity, .308 Win vs .300 Win Mag, .300 Win Mag vs .300 PRC, the new ammo of 2026, all ammo releases and all comparisons. See also .338 Win Mag vs .338 Lapua Mag.

Frequently asked questions

What is the SAAMI maximum pressure for .338 Lapua Mag and .300 Win Mag?

SAAMI lists 65,000 psi (transducer) for .338 Lapua Mag, and 64,000 psi (transducer) and 54,000 CUP (crusher) for .300 Win Mag, 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, .338 Lapua Mag or .300 Win Mag?

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 (.338 Lapua Mag ammo and .300 Win Mag ammo), which copy maker product pages, and from ANSI/SAAMI Z299.4.

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

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