My friend has a 7mm Weatherby Mag that was given to him by his grandfather. The .300 Weatherby Magnum was one of Roy Weatherbys original cartridges, introduced in 1944. 270 Weatherby Magnum Developed 1943 / Produced 1945 Was one of the first Weatherby Magnums offered to customers. In 1945, Roy Weatherby shortened the 300 H&H Magnum, blew out the body, necked it down to accept a 270 bullet and gave hunters a flatter shooting, harder hitting 270. by increasing bullet diameter by a mere 0.020 inches, Winchester widened the .284-inch bullet atop the 7mm Rem. Just as Remington stole the thunder of the .264 Win. case and greatly reduced its taper, thereby amassing additional space for propellant. by just 0.024 inches to create its .300 Win. It has the characteristic double-radius shoulders and is necked down to accommodate the .277 in bullets. It is based on a shortened and necked down .300 H&H Mag. Ideal for long-range, medium size game. I guess if a hunter wanted to forgo the .270 and .300 Weatherby, the 7mm Weatherby starts to make a bit more sense, especially when combined in a 2 rifle battery with something like a .340 Weatherby Magnum. It's too tight of a squeeze for me. It's a beautiful Mark 5 Weatherby. Mag. The .270 Magnum was the first case designed by Roy Weatherby, back in 1943, and it remains one of the most popular Weatherby calibers. A bit of cartridge trivia: As Roy Weatherby wildcatted what would become his Weatherby Magnum line, the shortened .270 Weatherby Magnum actually preceded his .30-caliber. Like I said its one of my three favorite calibers of all time. 257 Weatherby Magnum on left isn't as popular as 270 Weatherby and 300 Weatherby beside it, but more intriguing. The mighty .375 H&H Magnum produces only a few hundred more foot pounds of energy, which helps you understand why the .300 Weatherby is such a killing machine. The 7mm Weatherby is tightly shoe-horned between the .270 Weatherby and the venerable .300 Weatherby. 270, 300, & 338. As info, I found a chart on the Chuck hawkes website that shows the parent case for the 270 weatherby magnum is the 300 Holland & Holland magnum. The .270 Weatherby Magnum was the first belted magnum based on the .300 H&H Magnum to be developed by Roy Weatherby in 1943. The following ammunition cartridge ballistics information and chart can be used to approximately compare .300 Weatherby Magnum vs .300 Winchester Magnum ammo rounds. A turbo 270 WIN that shares a 2.545 length case with the 257, 270, and 7mm Weatherby Magnums. Nosler Reloading Guide No. Weatherby first shortened the belted, .300 H&H Mag. Mag. Mag. Please note, the following information reflects the estimated average ballistics for each caliber and does not pertain to a particular manufacturer, bulle I doubt that helps with any possibilities for lower cost availability though. A turbo-charged version of the popular 270 Winchester. Roy Weatherby introduced the .257 into his family of cartridges in 1948. Just doesn't get any better. The cartridge is short enough to function in standard-length long actions with a brass length of 2.549" or 64.74mm and an overall length of about 3.295". case with a sharp double radius shoulder (common to all Weatherby cartridges). BUY NOW The 257 Weatherby Magnum fits standard, 30-06-length actions; The 257 Weatherby can drive 75-grain bullets 4,000 fps; It pushes 120-grain deer bullets 3,200 fps; With less recoil, the 257 can put as much energy on target as a 30-06 There are lots of good .308 bullets available, and that's important, because at .300 Weatherby