350 Legend vs. 300 Blackout: Which is Better for You?

350 Legend vs 300 Blackout
February 14, 2022 Edited March 24, 2023 32143 view(s)
350 Legend vs. 300 Blackout: Which is Better for You?

Another in our series of caliber wars -- this time the older 300 BLK against the brand new (kind of) 350 Legend!

One designed for combat, the other for sporting, both of these AR-15 calibers are solid deer harvesting options -- but what is better?

We’ll dive into that and a whole lot more!


Design Intentions

350 Legend

One of the newest cartridges around, .350 Legend was released in Jan of 2019 from Winchester as a straight-wall mid-range deer slayer.

While named 350, the caliber is actually .357 and is thus legal in all of those odd states that still require a straight-walled rifle cartridge -- Michigan, Ohio, Iowa, and Indiana.

Why they require it is really just beyond my ability to understand, but at least they aren’t requiring shotgun and muzzle-loader only like they used to.

350 Legend was designed from the ground up to be able to serve those hunter’s needs. This is one of the purest sporting cartridges around today.

350 Legend Ammo on Workbench


300 Blackout

On the other hand, 300 Blackout was more designed for combat than it was for hunting.

The design intent was for a .30-caliber cartridge that shared as many parts with the standard M4 as possible and didn’t sacrifice any magazine capacity.

Mimicking 7.62x39 Soviet ballistics and functioning both in sub-sonic and super-sonic, 300 BLK was built to be a quiet, deadly, warfighting cartridge.

While it fills that role wonderfully, it also is a really good sporting cartridge.

For hunting hogs, deer, or home defense -- 300 BLK is a solid option.

300 Blackout Ammo on Workbench



When it comes to similar bullet weights and supersonic ammo, there really isn’t much difference between the 350 Legend and 300 Blackout ammo.

Bullet weights aren’t totally 1:1 but they are pretty close.

The most common 350 Legend weight is around 160-170gr FTX. 300 BLK supers come in a wide range of options, but 150gr is super common.

Side-by-side… they are really basically the same.

350 Legend vs 300 Blackout Ballistics Chart

Both are solid deer killers out to around 200 yards, but 300 BLK can go with a lighter bullet weight and push that to about 300 yards.

The drop is more or less the same within a few inches, lethality goes to 350 Legend but only because 300 BLK shines at a slightly lower bullet weight than 150gr.


Practical Applications

300 Blackout was designed as a combat cartridge, but it also has found a role in home defense and hunting. Ammo selection is great in both super- and sub-sonic while being easy to find in basically every LGS.

Something 300 BLK was designed for also is to work great suppressed, this it does very well and is one of the best AR-15 cartridges to throw a can on.

Able to take deer-sized game out to about 300 yards, 300 BLK is a solid all-round choice.

350 Legend on the other hand is a hunting cartridge, pure and simple. Subsonic ammo for 350 Legend is almost non-existent, and ammo selection, in general, is kind of poor since Winchester is basically the only brand that makes it.

Ammo is easy to order online, but finding it in-store can be very hit-and-miss -- even in straight wall cartridge states.

That said, this is a great deer dropper. Inside 250 yards, 350 Legend will harvest a deer in 1 clean hit.

[To learn more about Hunting with an AR-15, see our complete guide!]

350 Legend Rifle Slow Motion


Converting From 5.56 NATO

Shocking, the conversion process from a 5.56 NATO AR-15 (or any other AR-15 that uses a standard bolt) is the same for both 350 Legend and 300 BLK.

The easy method is a new upper. Take the old one off, throw the new one on, and you’re good to go.

But if you want to convert an upper all you need is a new barrel.

Both 350 Legend and 300 BLK use a standard AR-15 5.56 NATO bolt and bolt carrier. 300 Blackout works great in 5.56/223 magazines while 350 Legend works best in dedicated 350 Legend magazines. Just a barrel swap and grab a new mag and you’re ready to hit the range!


And The Winner Is…

Unless you’re in a straight-wall state, there really isn’t a great reason to get 350 Legend. 300 BLK can do everything 350 Legend can do plus a whole lot more and is cheaper, easier to find, and has a lot deeper selection. [See our Cheapest Ammo by Caliber 2022 infographic.]

Ballistics are so close together that there really isn’t a critical advantage to 350 Legend.

But if you are one of those midwest souls that just have to have a straight wall, then 350 Legend is a clear choice.

350 Legend is a great cartridge and serves the niche it was designed for very well. That might be basically all it does, but it does it well.

350 Legend and 300 Blackout Bullets and Magazines


Wrapping Up

In the end, both of these are great calibers, but one is definitely a lot more flexible and useful than the other.

However, if you’re suffering under the oppression of legal constraints that make no sense -- then you do what you gotta do. As a gun nut living in California, I get it. A less-than-perfect work-around is better than nothing.

[We'd like to extend a huge thanks to David Lane for his hard work on this article! For more helpful guides check out 6.5 Creedmoor and 7.62x39 vs 5.56.]


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February 15, 2022
350 is less than half the price of 300blk
February 16, 2022
February 15, 2022
I was under the impression that the 350 legend needed a specified 350 magazine. I tried loading the bullets in a standard 5.56 mag and they did not load correctly. I since purchased a mag specified for the 350 legend cartridge. I'm unsure of whether or not the 300 works in standard 5.56 mags. Could be another pro to that caliber.
Phillip D Lawson
February 16, 2022
I have a 5 rd Ruger 350 mag but I can not get a bullet to load into thee chamber ... it goes up the ramp and hits the roof of the chamber, jamming
February 18, 2022
300AAC works fine in a standard AR magazine, in my experience. The article even states that 350 should be used in dedicated 350 mags for best results.
Danny Willard
February 18, 2022
It does require a dedicated magazine. Try Ruger.
February 21, 2022
The 350 requires it's own mag, the 300 uses the same 556/223 mag just like 6.5 grendel uses a different mag and the 224 valkyrie and 6.8 share the same mag it's all in the parent cartridge and the feed ramps of the mag
February 16, 2022
It's been my experience that 350 Legend won't work in a 5.56 gen 3 P Mag. I couldn't get more than two rounds, Winchester 145 fmj, in a ten round (NY, what can I say) mag. Not a problem with supersonic 300 BLK, took all ten rounds.
Jack Langley
February 16, 2022
Magpul makes designated 300BLK/7.62x35 that work better than some 5.56/.223 mags. (PMAG 20AR 300 B)
Rod Carra
February 17, 2022
Couldn't agree with you more Jack. I own a couple of 300 Bko P-Mags and never had any issues with it. They make them for a reason.
Phillip D Lawson
February 16, 2022
also ... the 350 is straight wall and it is pushed inward because of the guide rib running down each side ... Pmag says do not remove it .. yes I tried it and it still will not load ...
Herbert Carrico
February 17, 2022
I need an AR barrel om1: 10 twist for 350 legend ??
Kevin C
February 17, 2022
If the 300blk had been designed so that it wouldn't chamber and fire in a 5.56, I would own one.
David DeFevers
August 19, 2022
The 300 blackout will fit in and feed from a 5.56 X 45 magazine, but it will NOT feed and fire in a 5.56 X 45 barrel.
November 6, 2022
Oh yes a 300BLK will chamber in a 5.56 barrel and fire. The bullet won't go down the barrel and you will grenade your right.
November 16, 2022
Nope. Think! How would a 7.62 projectile fit inside a 5.56/.223 chamber? It's the other way around, where a 5.56 cartridge could be chambered and (yikes) fired in a .300BLK rifle.
February 22, 2022
The 350 legend was first announced as being .357. It is NOT. All reloading data shows the bullet at .355. Why Winchester did that is beyond me. There already .357 bullets designed for rifles. 355 ala 9mm has always been a pistol bullet. Also besides Winchester, Hornady, Federal and Browning sell ammo for the 350 legend.
Steve Huey
February 24, 2022
I have bought 3 guns from Bear Creek. 5.56x45 7-1/2 pistol. 16 5.56x45 Rifle 20 inch SS 350 Legend. All these are accurate. I will buy again. When you order you get it quick. Plus lifetime Quarantee.
Ron Kitzman
April 1, 2022
I purchased a stainless steel 350 Legend from Bear Creek Arsenal. Went out and shot it today with 150 grain 350 Legend ammo. The blowback isn't enough to engage the next Shell out of the clip. I can manually load the next round but after firing it will not pick up the next bullet and you can't even pull the trigger like it loaded something. Anybody tell me what's wrong. I bought two five round clips from cmmg.
June 10, 2022
My 350 gave me feed problems. After tons of research and to make a long story short, I simply had the feed ramps polished and purchased an L5awm magazine. My 350 legend runs like a well oiled machine now. I hope this helps.
Chris Wyatt
June 28, 2022
I have two .350 legends and both had feeding issues, what I’ve found also is the follower in the magazine. I replaced all my followers with anti tilt followers and my feeding problems disappeared. With one exception, Hornady 170gr will not feed in my guns, I believe the issue is the overall length of the round, it’s just a tad to long and jams. I took a nice 150lb buck with my 20” 350 this past deer season, using Winchester 160gr PDX !
August 19, 2022
try using a carbine or pistol length gas tube/barrel & adjustable gas block.
Larry King
August 19, 2022
My local box store (Wal-Mart) has stacks of 350 legend for a long time now (even during the great ammo crunch) but 300 blackout not so much. So I switched to 350 legend
August 26, 2023
I live in Indiana, Walmart here I've asked about the 300 black out. They don't order or get them. Just the 350 legends which are always on shelves. Recently there shelves are now plum full with all cartridges.
Michael McInnis
August 19, 2022
The 300 Blackout is more reliable when firing supers out of 556 mags. Same when firing fat subsonic loads out of a purpose built magazine. Mag capacity is the same as 556. It has been my experience that 350 legend is unreliable in an AR-15 platform. So much so that I got rid of mine
August 19, 2022
The 300blk was designed to run suppressed and eat from an issued Colt stamped metal magazine. I have run this suppressed system under "do or die" situations and I'm alive today to tell you that if you can get ahold of M16 or M4 mags (Colt p/n 33710) you will not have a feeding problem. Even when you're " Spraying and Praying"! Now as a civilian I have tried just about mag out there and wound up back to using metal mags.
August 19, 2022
To compare ballistics you also should include energy at the various ranges. Also the 300 is not a good deer cartridge to 300 yards. You are stretching it quite a bit.
Christopher Collins
October 13, 2022
It is according to what ammo used in the 300 blk. It does carry enough energy to ethically kill a deer at 300 yards with some 110gr and 125gr ammo.
August 19, 2022
In my area when the shelves were bare, you could find 350 and almost nothing else. Walmart will sell 350, but will not sell .556 or 300. My BCA upper is shooting a one hole group.
Jimmy Derr
September 17, 2022
300 blackout is an excellent Deer round! I took a Buck at 75 yds with a CVA pistol chambered in it! Never knew what hit him!
Kevin F Volz
November 11, 2022
Concerning the use of the 350 Legend in Michigan, it's not the entire state that has to use straight walled cartridges, just the southern more populated part of the state which previously was relegated to muzzleloaders, shotguns and straight walled pistol cartridges. The MDNR thinking was these were all short range guns where the chance of a projectile traveling past it's intended target and striking an innocent victim was lower with the short range guns. It is my understanding Bushmaster approached these states with the ideal of a lethal short range cartridge with a straight wall to fit the definition under the law which was the 450 Bushmaster. These states approved the 450 Bushmaster which opened the door for the 350 Legend. The 450 BM was a huge success with hunters with the 350 Legend finding success also because is ballistically close to the .30-30 which is popular in the north woods without the recoil of the 450 BM. Michigan's Upper Peninsula and Northern Lower Peninsula are both open to using most centerfire rifle cartridges. Much of Michigan's northern forests hunting are short range shots, under 150 yards which cartridges like the 45-70, 450 BM, the .30-30 or 350 Legend are very capable at especially when in a short, light, quick handling rifle like a lever action or the modern AR platform making them very good choices for Michigan hunting. Hoefully this better helps you understand why Michigan has this law. I'm not saying I totally agree with the law but I do agree with prohibiting long range rifles such as the 7mm Mag, .300 Win Mag, etc where population density is higher. . Michigan has a preemptive law prohibiting local communities from regulating firearms which is great for firearm owners and people who possess CPLs from having to deal with a patchwork of gun laws but at the same time the state regulates what can be used for hunting in a certain area. The trade off is a win in my opinion. Last thing of note is I am a believer that the right to keep and possess firearms shall not be infringed but having been a hunter for just short of 50 years, I kind of agree that some limits on what can be used for hunting in certain areas having seen some people out hunting commit very unsafe acts.
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