February 25, 2019
By Layne Simpson
The 24 Nosler was designed by Mike Lake, who is the Senior Manager of Engineering, Research, and Development at Nosler. His previous accomplishments in the world of cartridges are the 26 Nosler (2013), 28 Nosler (2015), 30 Nosler (2016), and the 33 Nosler (2017). All are based on the .404 Jeffery case.
Then came the 22 Nosler, which was designed to deliver higher velocities in AR-15 rifles than the .223 Remington. It combines the rim diameter of the .223 Rem. with the larger body diameter of the 6.8mm SPC. Its to-the-brim water capacity is around 36.0 grains—about 5.0 grains more than the .223 Rem. and about 7.0 grains less than the .22-250. And since maximum cartridge lengths for the 22 Nosler and .223 Rem. are the same at 2.260 inches, an AR-15 in .223 Rem. is easily converted to 22 Nosler by switching uppers and buying a 6.8 SPC magazine.
Switching to 24 Nosler is just as easy. Nosler is first offering it in the Model 48 bolt-action rifle with the Armageddon AR-15 and a new long-range pistol on the Model 48 action to follow.
24 Nosler: Created for the AR-15
Simply neck up the 22 Nosler case for 0.243-inch bullets and you have the 24 Nosler, correct? Well, not exactly. Had the cartridge been designed for a bolt-action rifle with enough magazine length to handle a cartridge that long, that would have been the logical route to take. But the 24 Nosler was designed for the AR-15, and if an extremely long .24-caliber bullet, such as Nosler’s 105-grain Custom Competition, were seated into a necked-up 22 Nosler case at a cartridge overall length compatible with an AR magazine, the mouth of the case would be positioned far out over the ogive of the bullet. Shortening the 22 Nosler case 0.160 inch put the entire neck of the 24 Nosler case in contact with the full-diameter shank of the 105-grain bullet.
The chamber throat and leade of the 24 Nosler were dimensioned to handle not only extremely long match bullets, but also shorter bullets suitable for use on deer-size game as well as even shorter varmint-weight bullets. The neck of the case is long enough to exert adequate tension on bullets for uniform propellant burn while offering plenty of length for seating bullets longer to compensate for eventual throat erosion. Considering the small powder charges burned by the 24 Nosler, many rounds should have to be fired before chasing the rifling becomes necessary.
A chamber throat diameter of 0.2435 inch is only 0.0005 inch larger than a 6mm bullet, and that helps in aligning the axes of the bullet in a chambered round and the bore. Maximum chamber neck diameter is 0.270 inch. Neck diameter of my handloads was 0.266 inch, and factory ammo should be close to that. Respective bore and groove diameters are 0.237 and 0.243 inch. According to the SAAMI drawing I have, chamber pressure was set at 55,000 psi, and nominal velocity of a 105-grain bullet from a 24-inch barrel at that pressure is 2,575 fps.
24 Nosler Case Powder Capacity
Its powder capacity puts the 24 Nosler in very good company in terms of accuracy potential. During the 1950s and ’60s, the 6x47mm on the .222 Remington Magnum case absolutely owned Sporter Class in Registered Benchrest competition. The 6mm PPC replaced it and the .222 Remington during the 1970s, and in addition to setting more accuracy records than any other cartridge, it continues to dominate short-range benchrest competition. When filled to the brim, water capacities of the 6x47mm and 6mm PPC are 32.2 and 33.5 grains respectively. The 24 Nosler case holds 27.9 grains, and a closer match to it at 30.4 grains is the 6x45mm on the .223 Rem. case. Because the 6x45mm and 6x47mm are considerably longer from head to shoulder, they will not chamber in a 24 Nosler rifle, just as the .223 Rem. won’t chamber in a 22 Nosler rifle.
When this report was written, Nosler had not finalized the exact dates of its 2019 product launches, and that included the Armageddon AR-15 in 24 Nosler and loaded ammunition for it. The load data I received in May 2018 for 55-, 85-, 90-, and 105-grain bullets was shortly thereafter posted on the Nosler website. Unprimed cases in 100-count prepped and 250-count unprepped packaging were scheduled for late 2018. In June Dave Kiff at Pacific Tool & Gauge started shipping chamber reamers for the 24 Nosler as well as the 20 Nosler (more on it a bit farther on).
Redding was first to produce 24 Nosler reloading dies, but RCBS, Hornady, Lyman, Forster, and other companies will surely be offering them by the time you read this. So for those who cannot wait for factory rifles and ammunition, everything needed is out there for handloading, and gunsmiths across the country are ready and willing to take on your rebarrel job or a complete custom build.
As I mentioned earlier, a SAAMI maximum overall cartridge length of 2.260 inches for the 24 Nosler ensures that all factory ammunition will work in the AR-15 magazine. When hand-loading for a rifle with a longer magazine, that restriction can be ignored if its chamber throat is long enough to handle longer cartridges. When putting together ammo for the Nosler Model 48, I found it to be capable of handling cartridges exceeding 2.300 inches in length, and that allowed the extremely long match bullets to be seated with almost no intrusion on the powder cavity of the case. More specifically, with the Nosler 105-grain Custom Competition seated for a cartridge length of 2.350 inches, its base is positioned only slightly below the body/shoulder juncture of the case.
24 Nosler Range Results
Only a few Nosler Model 48 Liberty rifles in 24 Nosler had been built when I received mine; full production was still months away. On the short action, it weighs 7.75 pounds, and a Nikon 4-16X in a Talley lightweight mount increased that to an ounce over nine pounds. The 24-inch barrel measures 1.163 inches at the receiver and 0.655 inch at the muzzle. The six-groove rifling twist rate is 1:8 inches. The magazine holds six rounds.
One of the first things I do when I receive a test rifle is examine its bore with my Lyman Borecam. The rifle had obviously been shot a bit, but its bore was clean with the exception of a light trace of copper fouling in the leade and a few small patches of ironed-in powder fouling out toward the muzzle. A few minutes work with a brass brush, Shooters Choice, and Barnes CR-10 took care of that.
The load data sheets sent to me highlighted three powders as having produced the best accuracy with various Nosler bullets in Nosler’s test rifle. They were Reloder 7 with 55-grain bullets, Varget with 85- and 90-grain bullets, and Benchmark with 105-grain bullets. Best-accuracy charge weights with those powders were 24.0 grains for 55-grain bullets, 23.5 grains for 85- and 90-grain bullets, and 22.0 grains for 105-grain bullets. The highest velocity generated with 55-grain bullets was 3,424 fps compliments of Accurate 2230. The other speedsters were CFE 223 with 85- and 90-grain bullets (2,771 fps) and CFE 223 again with 105-grain bullets (2,625 fps). Those velocities were from a 24-inch pressure barrel, and we all know that pressure barrels with their absolute minimum chamber and bore dimensions deliver considerably higher velocities than most off-the-shelf rifles.
It was breezy on test day, so I put out the flags. It was also quite hot, and even with the stingy powder charges burned by the 24 Nosler, the barrel of the Model 48 heated up rather quickly. I fired four, five-shot groups with each of the 12 loads and water-cooled the barrel between each pair of groups. Three patches through the bore to remove any remaining water followed by one fouling shot and the rifle was ready for the next pair of groups. At 0.480 inch, the smallest single group by a considerable margin was compliments of the Lapua 90-grain Scenar and Varget. Four bullets went into 0.157 inch and then came that darned flyer.
Earlier I mentioned the 20 Nosler. It has been registered with SAAMI, but when it will be officially introduced by Nosler is anybody’s guess. Like its two littermates, maximum overall cartridge length is 2.260 inches, but since 0.204-inch bullets are shorter than 0.224-inch and 6mm bullets, its case is longer than the 22 Nosler case at a maximum of 1.850 inches, which just happens to be the same as the .204 Ruger. With a capacity of 39.0 grains (versus 33.0 grains for the .204 Ruger), the fatter 20 Nosler case just might be as much faster than the Ruger cartridge as the 22 Nosler is to the .223 Rem. Redding 20 Nosler reloading dies on my shelf are eager to find out.