TESTED: NEW CMMG 350 Legend Resolute AR-15

This year at the 2019 SHOT Show, the big news in new cartridges was 350 Legend from Winchester. I had the opportunity to talk with Winchester (see this story), and CMMG as well (see this story).  One of the big announcements that CMMG made was their 350 Legend AR-15 from the Resolute line-up (the first commercially available AR chambered for this new cartridge).

Fortunately, I’ve been able to get my hands on one of these rifles, and that’s the topic of this article: my first first-hand experiences with 350 Legend and my CMMG Resolute 300-series AR-15 chambered in 350 Legend. Just in time for deer hunting season!

CMMG Resolute 350 Legend Overview

CMMG offers three AR-15 rifles chambered in 350 Legend: the basic 100-series Resolute, the enhanced 200-series Resolute 300, and the flagship 300-series Resolute. The 350 Legend rifle shown in this article is a 300-series Resolute 16″ carbine chambered in 350 Legend.

From the CMMG product page:


CMMG’s RESOLUTE lineup is engineered with purpose for those who refuse to compromise on quality. Each RESOLUTE rifle comes with a 16-inch barrel and is designed for balance, accuracy and maneuverability. The RESOLUTE lineup is available in three tiers —RESOLUTE 100, RESOLUTE 200 and RESOLUTE 300 — that cater to your intended needs and customization. Whether you’re defending your family or looking to bring out your best at the range, the RESOLUTE keeps going when you need it most.

All RESOLUTE 300 Series rifles feature the following:

      • CMMG RipStock with 6 Position Enhanced Receiver Extension
      • Magpul MOE Pistol Grip
      • SV Muzzle Brake
      • Geissele SSA Trigger with Magpul MOE Trigger Guard (except for billet models that are integrated)
      • RML15 M-Lok Hand Guard
      • SBN Barrel
      • Ambi Charging Handle
      • Ambi Selector Switch
      • Ambi End Plate
      • CMMG’s Lifetime Quality Guarantee


      • CALIBER: .350 Legend
      • BARREL: 16.1″, 1:16 twist, Medium Taper, 4140CM, SBN
      • MUZZLE: CMMG SV Brake, threaded 1/2-28 (9mm)
      • GAS PORT LOCATION: Carbine Length
      • RECEIVER: Forged 7075-T6 AL M4 type upper, AR15 type lower
      • HAND GUARD: CMMG RML15 M-Lok hand guard
      • FINISH: Cerakote Receivers and Hand Guard
      • CHARGING HANDLE: CMMG Oversized Ambi
      • PISTOL GRIP: Magpul MOE
      • BUTT STOCK: CMMG RipStock with 6 Position Enhanced Receiver Extension and Ambi Sling Plate
      • TRIGGER: Geissele Automatics SSA 2-Stage
      • TRIGGER GUARD: Magpul MOE
      • MAGAZINE: Proprietary 10rd steel magazine
      • WEIGHT: 6lbs 5oz
      • LENGTH: 32.7″(stock collapsed)

Here’s what’s in the box (300-series, as shown in video):

Above we have:

  • Rifle
  • Instruction booklet
  • Magazine (*two shown here, rifle ships with one)
  • Slip 2000 lubricant

The Burn Bronze Cerakote that I selected (you can pick from numerous colors) is absolutely BEAUTIFUL! (click/tap to enlarge)

Setting Up the Rifle

My process for initially setting up the rifle was as follows:

  1. Install ATN X-Sight Pro 4K scope with ATN quick-change 30mm scope mount
  2. Install M-LOK bipod adapter (for Harris Bipod)
  3. Install Harris S-BRM 6″-9″ notched leg bipod

That was enough to get me on target at 100 yards. Using the one-shot zero function on this scope was helpful to get zero-d quickly, but it does require a large target especially if you are moving between rails with different inclination angles like I did in this case (from 20 MOA to straight/0-MOA). The X-Sight Pro 4K scope is a great option for close-to-medium range hunting, and I love the built-in video recording (I consider this a must-have now for big game hunting).

Above: Deer captured at the Ultimate Reloader ranch with the X-Sight Pro 4K (out of season unfortunately)

Later I installed a TriggerTech AR Diamond trigger and Magpul MOE Rifle (fixed version) stock for my bench and prone accuracy testing at 100 yards. My goal was to isolate all variables from the inherent accuracy of this rifle.

100 Yard Range Results

The 350 Legend cartridge is intended for hunting big game at ranges up to 250 yards, and was specifically designed to comply with straight-wall-only hunting requirements that are imposed in certain states for game like deer. A derivative of 223, but with a straight wall, this cartridge headspaces off the case mouth. And that’s something you’ll encounter more frequently with handgun cartridges! For these reasons, extreme accuracy was not a part of the 350 Legend design criteria.

If you click on this thumbnail, you can check out the full 350 Legend cartridge and chamber dimensions on the SAAMI website:

Early Results with Winchester Ammunition

Before I get into some of the results from my testing, I’ll note that I got some of the first commercial ammunition from Winchester in two varieties: 350 Legend 145 grain White Box, and 350 Legend 150 grain Deer Season XP. My initial results were all over the place. Some groups were in the 2″ range, and some more (over 3″). After talking with both CMMG and Winchester I found out that there were some issues that Winchester had addressed in later batches/lots of this ammunition. I had to wait a while, but eventually got some of the “updated” ammunition to test with. The updated ammunition shot much better, and the results from that testing of updated ammunition are what I’ll share below.

Factory Ammunition Tested

For this article, I had three types of ammunition to test, from left to right:

100 Yard Test Setup

For the testing results published in this article, I used the following setup and process:

  1. CMMG Resolute AR-15, 16″ barrel, AR Diamond trigger from TriggerTech, Magpul MOE rifle (fixed) stock
  2. Harris S-BRM bipod
  3. All shots fired from table with Wiebad Fortune Cookie rear bag
  4. ShotMarker e-target system with integrated chronograph (see note below for velocity data)

Best 100 Yard 5-Shot Groups

I consider 5-shot groups to be the minimum bar for “statistically relevant” testing of ammunition and rifles. So all groups listed in this section are for 5 consecutively fired shots at 100 yards.

Brand Series Bullet Weight (gn) Best Group (in)
Winchester White Box 145 1.55
Winchester Deer Season XP 150 2.02
Federal Power Shok 180 1.14

The best group from all of the testing was a 1.14″ 5-shot group using the Federal 180 grain Power Shok ammunition:

Field Shooting with 350 Legend

Shooting groups from a bench is really not the best way to evaluate 350 legend (it’s not a long-range cartridge or file platform). So I decided to shoot this Resolute 300 at 100 yards, with the goal of “lethal deer hunting accuracy” shooting from a kneeling position. Here’s a screenshot from the video in this article showing my setup:

Here are the three views shown in this frame:

  • Upper left: view through the ATN X-Sight Pro 4K scope (note hovering drone)
  • Upper right: Drone view of 10″ x 10″ steel target (100 yards from firing line)
  • Bottom: Camera at firing line

After some practice, I found it pretty easy to hit this steel target 5-6 times in a row from this position. And I also got hooked on this shooting setup (my first rifle shooting with this target at 100 yards). After this shooting session, I feel confident that I could kill a deer with this rifle from a kneeling position. With some practice, I think a 200 yard kneeling shot could be ethical (I’d have to try and practice to be sure!).

From Chuck Hawk’s article on American big game:

For example, an average whitetail deer weighing about 125 pounds, viewed broadside, has a heart/lung area generally estimated give you a circle of around 10″ in diameter at which to shoot. If you can keep your bullet in a 10″ diameter circle from a field position and you aim just behind the foreleg and about 1/2 of the way up from his brisket (or 1/2 of the way down from the top of his back), which basically marks the center of his heart/lung area, your bullet should find the animal’s vitals.


350 Legend is an interesting cartridge, especially for folks in straight-wall cartridge hunting states. I really like my CMMG Resolute 350 legend rifle, and feel like it would be a great choice for deer hunting at ranges spanning 100-200 yards or so. With the ability to place quick follow-up shots, an AR-15 makes a lot of sense, and this rifle/cartridge combination gives you that ability in straight-wall only hunting areas. With many ammunition options already on the market, this combination would be a great hunting setup for the 2019 deer season!

I’m also quite curious to start handloading for the 350 Legend. I’ll be following up with that shortly! I’m also curious to hear what you think of 350 Legend, and the CMMG Resolute AR-15 lineup. Please leave a comment!

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