.300 Jarrett
150 gr. Nosler Bullet..................3550 to 3600 fps
165 gr. Nosler Bullet..................3400 to 3450 fps
180 gr. Nosler Bullet..................3200 to 3250 fps
200 gr. Nosler Bullet..................3000 to 3050 fps
Since the conception of the .300 H&H Magnum hunters and target shooters alike have realized the potential of thirty caliber bullets at high velocities. The .300 Winchester Magnum and the .300 Weatherby just further validated in people’s minds how good they really were for long range shooting. Having produced a lot of Jarrett Rifles in the .300 Win Mag caliber we realized that we could consistently derive extremely good accuracy and performance from this cartridge. With the .300 Weatherby’s we could get the velocity, but the accuracy was erratic due to the free-bore design. The free-boring or clearance in front of the bullet before the rifling was a necessary design, when Mr. Weatherby created that cartridge, due to the powder selections that he had to work with at the time. At this point, our direction was to achieve the Weatherby ballistics, or better them if possible, combined with the inherent accuracy of the .300 Winchester Magnum
We chose the 8mm Remington Magnum case, because in a blown out improved configuration it would give us the case capacity we needed. The brass is very tough and inexpensive compared to Weatherby brass. A 35 degree shoulder angle was chosen for the new cartridge. We arrived at a lead angle in the throat area of the chamber (That is Classified Information). I’m sure similar cartridges have been developed and used, but our advantage was all of the new slow burning powders available today, and a larger variety of bullets and primers.
After all of the homework and reamers were finished, we made two test rifles. Our results with these two test rifles proved to be a good representative example of the .300 Jarrett’s potential. With the 165 grain Nosler Ballistic tip bullet, the velocities ran from 3350 fps to 3450 fps, with minute, three shot accuracy at 100 yards from an 8 pound rifle. The 180 grain Partitions went from 3150 to 3250 fps. With identical powder charges used in the .300 Weatherby, we got increased velocities in the .300 Jarrett of 100 to 150 fps, proving it to be a more efficient case. It will consistently deliver a 200 grain Nosler Partition at 3000 fps average. At this point, I knew I had a winner with the cartridge that would be the ultimate long range deer rifle with 165 grain bullets. To add icing to the cake, at 250 yards, the .300 Jarrett with a 200 grain bullet (muzzle velocity 3000 fps) has more energy than a .338 Win. Mag. with a 250 grain bullet (muzzle velocity 2700 fps). This flatter trajectory and higher energy levels beyond 250 yards would make the .300 Jarrett a better long range elk rifle. For the one rifle advocate, this combo will come closer than anything I know of at the present time, especially with the unbelievable consistency in accuracy using different bullet weights.
To make the .300 Jarrett we run the 8mm Rem Mag brass through a Redding .300 Jarrett full length die. We then load 79 grains of H1000 powder with any 180 gr. 30 caliber bullet and fire it in the rifle. That’s all there is to it. You can also use .375 brass which is the same length as 8mm Mag brass. As an emergency alternative .300 Weatherby ammo can be safely fired in the .300 Jarrett, but the fired case cannot be reloaded because the neck area is too short after firing. The .300 Jarrett is here to stay, because it gets the job done with authority on targets, deer, elk and most of the African animals. It has become my own personal favorite and our number one seller!
