November 09, 2021
By Michelle Hamilton
The 350 Legend from Winchester/Olin Corporation has made quite the splash since its introduction at SHOT show in 2019. This straight-wall cartridge is designed primarily for hunting medium-sized game in states where bottlenecked rifle cartridges are not allowed. Winchester claims that the 350 Legend is the "fastest straight wall cartridge" and with the exception of boutique cartridges such as .444 Marlin offerings from Buffalo Bore and Underwood, they are correct. The 350 Legend offers obvious performance advantages for brush heavy areas and has proven itself on whitetails, but does it have uses outside of "straight-wall states"?
The 350 Legend uses a .355-.357-inch diameter projectile typically weighing from 160 to 180 grains. It propels these "heavy for caliber" projectiles into the low to mid 2,000 feet per second range. With this in mind, how would this hybrid intermediate power rifle/big bore handgun cartridge conglomerate, rank for practical defensive usage in a real world scenario? The 350 Legend cartridge case’s exterior dimensions are extraordinarily similar to that of a straight 5.56mm case and feature the same 0.378-inch nominal rim diameter and 2.26-inch overall cartridge length. This allows the use of standard 5.56mm bolts and carriers, making cartridge conversions simple in AR-15 pattern rifles. It just takes a barrel and magazine swap to convert from 5.56mm to 350 Legend.
While proprietary or modified AR-15 magazines are necessary for this cartridge, capacity easily exceeds that of other "big-bore AR" cartridges. Fat cartridges like the .458 SOCOM and .50 Beowulf single-stack in an AR-15 magazine, greatly reducing capacity. The 350 Legend doesn’t have this issue. While modifications can be done to Magpul 5.56mm 30-round PMag magazines (which will be covered), C-Product Defense produces a steel 20-round magazine, which I have had stellar results from. The 20-round magazines provide a sleek and compact profile, without greatly sacrificing ammunition capacity. For my personal uses, the CPD steel 20-round magazines are the perfect fit for this caliber.
What exactly would the 350 Legend bring to the table over the more popular 5.56mm? Simply put: mass, larger diameter projectile and deeper penetration. The 350 Legend puts a larger and heavier payload on target. The flip-side is the 350 Legend has a shorter practical range and drastically reduced muzzle velocity. A Winchester 180-grain 350 Legend Soft Point load chronographs at 2,037 feet per second from a 16-inch Faxon Gunner series barrel and provides a respectable 1,658 foot pounds of muzzle energy. This is a loss of 63 feet per second, or a 3% decrease from Winchester’s advertised velocity.
In comparison a 5.56mm 55-grain Hornady Soft Point offering from their TAP "training" line of ammunition (a popular defensive offering, one with respectable performance and one that is typically readily available) will offer a muzzle velocity of 2,891 feet per second from a typical 16-inch barrel, mid-length gas system AR-15. While you will note a 29.89% decrease in muzzle velocity from 5.56mm to 350 Legend, this loss is counteracted by a 227.27% increase in mass and a 59.37% increase in projectile diameter. It is also noteworthy that the 350 Legend produces substantially deeper penetration than most offerings in lighter full-sized rifle cartridges, such as the .243 Winchester and even producing penetration depths that rival the popular 30-30. So, with that said, how can all this added mass and weight produce a potentially more effective defensive firearm than the popular 5.56mm?
The short answer is barrier penetration. The 350 Legend is a viable option for those who may need to effectively punch through light to medium barriers (such as windshields or auto body panels), while wanting a lighter recoiling and more compact platform than a 7.62x51mm NATO battle rifle. The 350 Legend has an effective range that mimics that of an intermediate power rifle cartridge (0-300m) and has advertised retained performance at 300 yards much like that of a .357 Magnum at the muzzle. This performance surpasses that of the .357 Magnum from a carbine or rifle length barrel and places the performance level on par with the .357 Remington Maximum (the "hand loaders delight") from an 18-inch barrel. Basically, the 350 Legend offers some serious performance in a lightweight and compact package.
Where can it be useful? The 350 Legend could be handy for certain types of armed security work, certain LE/police work, armed citizen personal protection and as a general purpose carbine on a ranch or farm (especially those who may be located in black bear country). The modularity of the AR pattern rifle allows switching from 5.56mm to 350 Legend by simply pushing out two pins and swapping uppers and magazines. It gives the user far more options than the run-of-the-mill intermediate power cartridge.
When I was purchasing 350 Legend at the end of 2019 and into 2020, ammunition cost was fair overall. It came in between the cost of brass 5.56mm and brass .308 Winchester with 350 Legend 145-grain FMJ from Winchester costing $7.99 per box and quality defensive and hunting ammunition between $.75 for Soft Point to $.90 per round for the tipped Deer Season XP from Winchester. Other companies (such as Precision One Munitions) produced a 147-grain XTP, high velocity defensive hollow point for a very reasonable $.65 per round. These prices are of course, pre-COVID and election.
While factory 20-round magazines fit my needs perfectly (as the 350 Legend is a relatively heavy cartridge), those with the proper tools and a bit of time can convert Magpul 5.56mm PMAG's to 30-round 350 Legend magazines. This requires the removal of the polymer guide on the interior of the magazine. This molded polymer guide is in place to not only add rigidity to the body of the magazine, but it also guides and aids feeding the bottlenecked cartridge, for optimal reliability. With this guide removed, the magazine will both hold and reliably feed thirty Legend cartridges.
The 350 Legend performed well from my AR, and proved extremely reliable with one exception, Browning's 124-grain FMJ offering. The projectile used in this load from Browning is essentially nothing more than a 124-grain .355-inch bullet loaded in the 9mm Parabellum cartridge, and did not work well with my AR-15’s feed ramps. The Browning offering is the only 350 Legend load I had issues with. I experienced two failures to feed from a box of 20 rounds. I personally believe this is the interaction between the feed ramps of the Faxon Gunner series 16-inch barrel used and the sub-optimal projectile choice by Browning.
With Precision One and Winchester, reliability was phenomenal. From bench shooting through drills and even the occasional mag dump. Accuracy was good overall, with surprising results from the Winchester White Box 145-grain FMJ. It wasn’t uncommon to achieve 2.5 to 3.5 inch 100 yard 5-shot groups from the White Box FMJ. Groups shrank drastically switching to the Deer Season XP load with my best 5-shot group measuring 1.75-inches at 100 yards.
I use a 2.5-10x Nightforce rifle scope and rifle bags for resting (along with a bipod when applicable) when testing for accuracy at 100 yards. For a 6-pound, lightweight "gas gun", I found accuracy of this 350 Legend to be unexpectedly good overall. A person should expect 2-inch groups from bulk factory ammunition and an AR-15 while a bolt-action should do even better.
The cartridge is promising in terms of accuracy. It is certainly more than adequate in terms of terminal performance and barrier penetration to be considered for effectively dispatching two and four legged foes. The projectile is less likely to deviate from harder barriers than lessor cartridges, and will carry more mass through barriers to effectively stop a threat. The 350 Legend offers great capacity considering its bore-size, a low recoil impulse, and an inexpensive entry into the "big-bore AR" scene in terms of ammunition cost and availability than the typical "big-bore" offerings (.458 SOCOM, .450 Bushmaster and the .50 Beowulf). Most of my 350 Legend ammo came from Wal-Mart, while grocery shopping. Dwell on that for a moment. While the cartridge does have its naysayers, the capabilities and performance makes for a promising caliber for multiple applications.
If you have any thoughts or comments on this article, we’d love to hear them. Email us at FirearmsNews@Outdoorsg.com.
About the Author:
Michelle Hamilton has a Bachelor’s degree in Criminal Justice/Homeland Security, is a serious student of wound ballistics, military history, small arms design and manufacturing and is a competitive shooter.