January 19, 2017
By Layne Simpson
Shooting the new-for-2015 .28 Nosler took me back to a hunt for black bear on Vancouver Island in May of 1999. It was the very first outing for a wildcat cartridge that I had recently developed, and Bob Chiusano, another hunter in camp, and I used my rifle chambered for it to take very good bruins.
His bear dropped in its tracks, as did mine except it rolled, tumbled, and bounced several hundred yards down the side of a very steep mountainside like a sack full of Jello. The handload we used pushed a 140-grain bullet along at 3,325 fps from the 26-inch barrel of a Canadian Gun Works M18-TI.
Our guides were quite impressed by the performance of the new cartridge. So was Bob Nosler, who was also hunting out of the same camp. One night over dinner he proclaimed, "If ever I get into the ammunition business, the 6.5 Shooting Times Westerner (STW) is a cartridge I will most definitely load."
True to his word, Bob finally got around to doing just that almost exactly one year ago, but he decided to use a shorter, fatter, nonbelted case, and he called it the .26 Nosler. Powder capacities of the 6.5 STW wildcat and the .26 Nosler are virtually the same, so velocities are the same when the two cartridges are loaded to the same chamber pressures and fired in rifle barrels of the same length.
Just as the 7mm STW is a necked-up version of the 6.5 STW, so it goes with the .28 Nosler and the .26 Nosler. When filled to the brim, the .28 Nosler case holds 100.7 grains of water versus 99.6 grains for 7mm STW cases made by Remington and 100.2 grains for those from Federal. Those are insignificant differences in cases of such large capacities.
SAAMI maximum overall cartridge length for the 7mm STW is 3.600 inches versus 3.340 inches for the .28 Nosler. Making the new cartridge shorter allows it to be used in the Nosler Model 48 rifle, the magazine of which is shorter than those in actions of standard length, such as the Remington Model 700 and Winchester Model 70. Making the cartridge fatter allows it to hold the same amount of powder as the 7mm STW.
The .28 Nosler is a shortened version of the 7mm Remington Ultra Mag. They share a maximum body diameter of 0.550 inch. Rebating the rim to 0.534 inch simplifies the production of rifle bolts since the rims of Holland & Holland-style belted magnums, such as the 7mm Remington and .300 Winchester, are the same diameter. Whereas the 7mm RUM case measures 2.387 inches long from head to body-shoulder juncture, that dimension on the .28 Nosler case is 2.166 inches.
The dimension at that point on the Nosler case is 0.002 inch larger and that reduces its body taper by just a tad. Maximum case lengths are 2.850 and 2.590 inches respectively. Shoulder angles are 30 degrees for the Remington cartridge and a slightly sharper 35 degrees for the Nosler. Due to its greater length, the Remington case is about 25 percent more capacious than the Nosler case.
The .28 Nosler case can be formed by running 7mm RUM or .300 RUM cases through a .28 Nosler full-length resizing die with its expander/decap assembly removed and then trimming to the proper length. But despite the best of efforts, case loss will be high due to wrinkling.
A case-forming die is available from Redding, and while I have not tried it, another Redding die on my shelf forms the 6.5 Remington Magnum and .350 Remington Magnum cases from the longer 7mm Remington Magnum case. Case loss is zero with it.
Only one form die is required to push the shoulder of the RUM case back to the .28 Nosler dimension. A form-trim die would be handy for removing the 0.250 inch of excess neck length, although doing so is quick work for power trimmers, such as the RCBS Trim Pro and Hornady Power Case Prep Center.
Trimming would finish the job unless the neck wall requires thinning by reaming or outside turning for the tight chamber neck of a particular rifle. I won't be surprised to see form dies become available from RCBS as well.
Two factory-loaded ammunition options will initially be offered, both under Nosler's Trophy Grade banner. One is to be loaded with a 160-grain AccuBond at 3,250 fps in a 24-inch barrel and 3,300 fps in a 26-inch barrel. The 175-grain AccuBond LR loading will arrive with 3,075 and 3,125 fps ratings.
In comparison, the 7mm Remington Magnum, as loaded by Remington with 160-grain bullets, is rated at 2,950 fps (standard) and 3,002 fps (Hypersonic). The 175-grain loading is advertised at 2,860 fps. The 7mm RUM is not offered with a 160-grain bullet at maximum velocity, but the 175-grain load is listed at 3,025 fps.
The 7mm RUM is an example of returns that have diminished to the point of nonexistence when a realistic powder charge to bore diameter ratio has been greatly exceeded. Maximum velocities with 175-grain bullets shown in five reloading manuals range from 3,077 to 3,164 fps with an average of 3,108 fps.
Loaded to the same chamber pressure of 65,000 psi, the .28 Nosler is capable of matching that muzzle velocity while burning less powder.
Since the .28 Nosler burns smaller powder charges than the 7mm RUM, barrel accuracy life is potentially a bit longer. How much longer depends on a number of things, including barrel quality and whether a barrel is pampered or abused by its owner.
The first rifle in 7mm STW built for me by Kenny Jarrett in 1987 still has its original barrel. I have not kept an accurate record of the number of rounds fired, but it has accounted for a lot of game during the past 27 years, including a record-book interior grizzly in Alaska in 2010. It still averages less than half minute of angle with its favorite loads.
The .28 Nosler has the same size appetite for powder, so all else being equal, barrel accuracy life will be the same for it. Few who own rifles chambered for the new cartridge and take good care of them will wear out a barrel during a lifetime of hunting.
The .28 Nosler will be introduced in the Patriot version of the Nosler Model 48 rifle. As should be for a cartridge of extremely low expansion ratio, barrel length is 26 inches.
Prior to shooting Shooting Times's sample rifle, I attached a Swarovski 2.5-10X 42mm scope, and that brought its weight up to 9.13 pounds. Three cartridges in the magazine and a carrying sling would nudge its hunt-ready weight close to 10 pounds.
The rush was on to get a rifle to me in time for the Shooting Times deadline, and at the time of its shipment, Nosler technicians were still in the process of finalizing dimensional and ballistics specifications for .28 Nosler factory ammunition. Among other things, maximum velocities and overall cartridge length had yet to be decided.
Since what would eventually be classified as factory-loaded ammunition was unavailable, they did the next best thing by sending along a couple boxes of cartridges loaded with the 175-grain AccuBond LR bullet that had been handloaded for a company employee hunt.
The Nosler rifle is designed to handle all bullets of its caliber made by Nosler, including the 175-grain Partition. When that bullet is loaded in the .28 Nosler to its SAAMI maximum overall cartridge length, a fairly long leade in the chamber of the rifle is necessary to accommodate its ogive shape.
The 175-grain Partition is a favorite among elk hunters who use various 7mm cartridges, so why this was done is quite understandable. But there is a downside to dimensioning a chamber for it when bullets of later design in the Nosler lineup differ so drastically in ogive length and shape.
In the ammunition included with the rifle, the 175-grain AccuBond LR with its extremely long and mildly tapered ogive was loaded to an overall cartridge length of 3.345 inches. During firing, the bullet had to free-travel 0.120 inch prior to engaging the rifling. In my experience, that's a bit much for best accuracy with AccuBond bullets, and holes punched in paper targets confirmed it.
Three-shot groups fired at 100 yards with the barrel cooled down completely between groups averaged 1.46 inches. That's accurate enough for a big-game rifle from a practical point of view, but many of today's hunters expect better.
Seeking an improvement in accuracy, I pulled the bullets from remaining rounds, dumped the powder, resized cases with the RCBS die, recharged them with the salvaged powder, and reseated bullets to an overall cartridge length of 3.405 inches. Doing so reduced bullet jump to 0.060 inch.
With an interior length of 3.420 inches, the magazine had no problem handling the longer cartridges, and they were still short enough to allow the ejection of a loaded round without the nose of the bullet hanging up on the front of the ejection port.
Making that small dimensional change along with an hour of thoroughly cleaning the barrel with Shooter's Choice powder solvent and Barnes CR-10 copper solvent trimmed average group size to 1.34 inches. An improvement for sure, but not enough to write home about.
My supply of Nosler-loaded ammunition was limited to 40 rounds, so I next turned to handloading. Being somewhat familiar with stuffing various powders and bullets into 7mm STW cases, I felt quite comfortable when beginning load development for the new cartridge with starting powder charges recommended for the old cartridge.
Unprimed .28 Nosler cases were not available, but the necks of .26 Nosler cases were easily expanded by one trip over the tapered expander button of the RCBS full-length resizing die. A second RCBS die was used to seat bullets.
Only a few 175-grain AccuBond LR and Partition bullets were on my shelf, but there was a good supply of 168-grain AccuBond LR and 160-grain AccuBond. Charges used with the four powders behind the 160-grain AccuBond pretty much duplicate the velocities we will see in Nosler's upcoming factory load with that bullet. The Nosler rifle indicated a definite preference for that bullet over the others I tried.
It is important to note that maximum powder charge weights ended up at several grains heavier than I customarily use in the 7mm STW in order to reach the same velocities with the various bullet weights included in my tests. There is not enough difference in the capacities of the two cases to account for such a difference in powder charge weight requirement, so it has to be due to the long chamber throat of the Nosler rifle. Be aware that while the loads included in this report were safe in the test rifle, they have not been tested for pressure.
For sharp-eyed readers who notice that Nosler's handload with the 175-grain AccuBond bullet exceeds the factory-established velocity rating by close to 100 fps, there is an explanation. When the ammo was loaded several weeks prior to my receiving it, a muzzle velocity of 3,200 fps from a 26-inch barrel had been decided on.
And it would have been no brag since average velocity in the rifle I shot was 3,217 fps. But somewhere along the way the decision was made to reduce velocity to 3,125 fps, and that's what you will see on factory packaging. I was told that 3,200 fps was reached without exceeding the SAAMI maximum chamber pressure, so the reduction likely had to do with case longevity.
As I discovered while handloading the cartridge, case life improves dramatically when the velocity of 175-grain bullets does not greatly exceed 3,100 fps. Case life is quite important to those who buy factory ammo and then reload the fired cases.
Rifles, ammunition, and unprimed cases in .28 Nosler are slated for availability during spring of 2015. Except for the procrastinators among us, that should give hunters plenty of time to fine-tune and dial in their rifles long before the bull elk start their bugling.