46 SEPTEMBER 2019 AMERICAN RIFLEMAN
WINCHESTER 350 LEGEND
slightly by also permitting the use of certain straight-
wall cartridges (that meet speci c projectile-diameter and
case-length parameters) for the purposes of hunting. As a
result, the few existing straight-wall ri e cartridges meet-
ing these criteria have experienced unexpected windfalls in
popularity, as sportsmen in the affected states have ocked
to them—with the .450 Bushmaster being perhaps the big-
gest bene ciary.
But, while a capable hunting round, .450 Bushmaster
remains expensive, elusive and a bit punchier on the
shoulder than some hunters may appreciate. Winchester’s
engineers felt they could do better on all three accounts,
and their research kept bringing them back to the .35
caliber. The ultimate fruits of their labor were submit-
ted to the Sporting Arms and Ammunition Manufacturers’
Institute’s (SAAMI) technical committee at the group’s
June 2018 meeting, and were subsequently accepted during
its January 2019 session—with 350 Legend’s maximum car-
tridge and minimum chamber standards entering the public
domain at that time. A similar process seeking approval
from CIP (Europe’s version of SAAMI) has already begun.
As far as cartridge design goes, it would be hard
to come up with something less complicated than the
350 Legend. Based loosely on the .223 Rem.’s case,
and using the same 0.378" case head and a similarly
rebated rim, the 350 Legend’s body measures 0.390"
wide forward of the extractor groove, and while it
obviously has no shoulder, the case does taper ever so
slightly back to 0.378" at its mouth to aid in extrac-
tion. Given its rebated rim and lack of a shoulder,
headspacing on the cartridge mouth (like the vast
majority of semi-automatic handgun chamberings) is
the only method open to 350 Legend.
Case length is speci ed as 1.710", compared to 1.760" for
.223 Rem., and case capacity averages around 36.5 grs./water.
Maximum Cartridge Overall Length (C.O.L.) is set at 2.260"—
identical to that of .223 Rem.—meaning that 350 Legend will
t in .223 Rem.-length actions without issue. Maximum average
pressure (MAP) likewise has been set by SAAMI at 55,000 p.s.i.,
again matching the .223’s standard.
Taken together, the two above figures (in conjunc-
tion with its identical case head) open 350 Legend up
to potential compatibility with the vast assortment
of .223 Rem.-chambered autoloaders on the market
(after a barrel change, of course), an exceedingly
forward-thinking decision on Winchester’s part. The
two cartridges’ geometries, however, differ enough that
dedicated 350 Legend magazines are required—the
guide ribs just forward of the rounds’ shoulders in .223
AR magazines preclude proper stacking of 350 Legend
within the detachable boxes—and standard .223 Rem.
magazines can’t just be modified by the end user.
On the positive side, 350 Legend’s case diameter allows for
the use of a double-feed magazine design, which means that
the new cartridge’s magazines are as quick and easy to load as
a standard .223 Rem. magazine. The dual, staggered columns
also mean that 350 Legend doesn’t suffer from the same
capacity penalty as does the .450 Bushmaster, which is broad
enough to require that the rounds be stacked atop each other
in a single pillar. As a result, a 10-round 350 Legend AR-15
magazine has the same familiar pro le as a 10-round .223
AR-15 magazine.
The dimensions published by SAAMI specify a bullet
diameter of “0.3570 – 0.0030,” which allows for some ex-
ibility on Winchester’s part, and pulling the bullets from
several loaded cartridges revealed that each was 0.355"
in diameter. This was a somewhat curious discovery, as
virtually all .35-cal. center- re ri e chamberings that
came before the 350 Legend make use of either 0.3585"- or
0.3590"-diameter projectiles, and bullets in the 0.354" to
0.357" range are more frequently encountered in hand-
gun cartridges. However, the company assures me that
the projectiles used in each of its 350 Legend loads
were speci cally developed for the new cartridge, were
designed to operate at ri e velocities and were not sim-
ply repurposed from the company’s handgun chamber-
ings of similar diameter.
Winchester is among the leaders in the entire ammuni-
tion industry in terms of high-volume production of both
.223 Rem. cases and .357-cal. projectiles, and by designing
350 Legend to essentially utilize both, the company can
bring major cost-cutting forces to bear in its manufacture.
All cartridge cases start life as “cups” that are stamped from
strips of brass. By using the same diameter case head for
both .223 Rem. and 350 Legend, Winchester can quickly
and easily convert a manufacturing cell fabricating one
cartridge to begin forming the other by just changing outFive 350 Legend loads were announced at the cartridge’s SHOT
Show 2019 launch, three of which were in production and
available on store shelves as of mid-June: (l. to r.) a 145-gr.
FMJ, a 150-gr. Deer Season XP and a 180-gr. Power-Point.