Head to head

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

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

This page puts .338 Win Mag and .338 Lapua Mag side by side using only our own ammo guides, .338 Win Mag ammo (7 loads) and .338 Lapua Mag ammo (12 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 and 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.

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

Measure	.338 Win Mag	.338 Lapua Mag
SAAMI name	338 WINCHESTER MAGNUM [338 WIN MAG]	338 LAPUA MAGNUM [338 LAPUA MAG]
Drawing issued / revised	04/21/1980 / 02/15/2022	01/14/2013 / 03/08/2022
Maximum average pressure (transducer)	64,000 psi	65,000 psi
Crusher pressure	54,000 CUP	Not established
Cartridge overall length	3.180 in min to 3.340 in max	3.5610 in min to 3.6811 in max
Case length	2.500 in (−.020)	2.7244 in (−.0201)
Bullet diameter (as SAAMI prints it)	.339 in (−.003)	.3390 in (−.003)
Bore / groove diameter	.330 in / .338 in	.330 in / .338 in
Twist and grooves	1 in 10.00, 6 grooves (marked optional)	1 in 10.00, 6 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 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 Win Mag loads in our table	.338 Lapua Mag loads in our table
Federal	test barrel not listed: 1 load, 200 gr, 2,930 fps	test barrel not listed: 2 loads, 250 to 300 gr, 2,580 to 2,950 fps
Remington	test barrel not listed: 2 loads, 225 to 250 gr, 2,660 to 2,780 fps	—
Hornady	24 in test barrel: 4 loads, 200 to 230 gr, 2,800 to 3,030 fps	24 in test barrel: 3 loads, 250 to 285 gr, 2,745 to 2,860 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

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 Win Mag	.338 Lapua Mag
Hornady Precision Hunter	230 gr ELD-X® Precision Hunter®, 2,810 fps, 4,032 ft-lb, 24 in test barrel, item 82222	270 gr ELD-X® Precision Hunter®, 2,800 fps, 4,699 ft-lb, 24 in test barrel, item 82313

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 64,000 psi (transducer) plus 54,000 CUP (crusher) for .338 Win Mag and 65,000 psi (transducer) (SAAMI establishes no crusher pressure) for .338 Lapua Mag. Source: ANSI/SAAMI Z299.4.
If bullet weight is your question: The .338 Win Mag loads in our table run from 200 gr (Federal Trophy Bonded Tip P338TT2) to 250 gr (Remington Core-Lokt 22191). 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). Sources: those maker pages.
If you want to see the printed velocities: the slowest and fastest muzzle velocities in our table: for .338 Win Mag: 2,660 fps, test barrel not listed (Remington Core-Lokt 22191) and 3,030 fps, 24 in test barrel (Hornady Superformance SST 82223). For .338 Lapua Mag they 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). 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 2.500 in (−.020), cartridge overall length 3.180 in min to 3.340 in max for .338 Win Mag; and case length 2.7244 in (−.0201), cartridge overall length 3.5610 in min to 3.6811 in max for .338 Lapua Mag. Check the cartridge named in your rifle’s manual or marked on its barrel. Source: ANSI/SAAMI Z299.4.

Not yet verified

Our .338 Win Mag table includes loads from Federal and Remington; the .338 Lapua table includes Federal, Hornady and the other makers shown, so the maker rows above differ by cartridge.
Winchester and other 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.
Some SAAMI fields are not recorded for .338 Win Mag and .338 Lapua Mag in our guides (marked above); we have not filled them from other sources.
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 Win Mag ammo and .338 Lapua Magnum ammo, plus .338 Lapua vs .300 Win Mag, .300 Win Mag vs .300 PRC, .308 Win vs .300 Win Mag, .375 H&H ammo, 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 .338 Win Mag and .338 Lapua Mag?

SAAMI lists 64,000 psi (transducer) plus 54,000 CUP (crusher) for .338 Win Mag and 65,000 psi (transducer) (SAAMI establishes no crusher pressure) for .338 Lapua 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 Win Mag or .338 Lapua 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 Win Mag ammo and .338 Lapua 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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