Thanks to the bottle necked metallic cartridge and smokeless powder wildcatters, as they were nicknamed, were getting results from their rifles, the likes of which had not been seen before.
While everyone has a different idea of what the perfect hunting cartridge might be. Some wanted faster and flatter shooting, others wanted a large bullet with lots of weight. Often it was the type of animal being hunted and the terrain in which the hunt took place that dictated what the "perfect" cartridge might be.
For the most part American hunters in the mid-western and western states prefer a mid sized bullet that was fast moving and had reduced bullet drop.
I won't go into detail on the "perfect" cartridge as that debate is as old as the metallic cartridge itself.
We could say the story of the .263 Sabre started with Charles Newton who, in 1912, modified the .30-06 Springfield cartridge by shortening it and necking it down from .308" to .257", creating the .25-'06 (later legitimized by Remington). A year later hid did the same thing with a 6.5 mm bullet, this time necking the Springfield cartridge down .001" smaller to .264 to accept a bullet from a 6.5mm Swede cartridge.
Newton also changed the neck angle and body taper. The neck was set at 23 degrees and the OAL is shorter that the 30-06.
It was inappropriately named the the .256/06 or simply the .256 Newton. Why he named it the .256 I don't know, the bullet diameter is actually .264", it isn't even 6.5mm, actually a 6.71mm, see my write up on cartridge naming conventions here.
Other wildcatters had done similar work by simply resizing 30-06 brass to .264 and using surplus Swedish military bullets, creating what was universally known as a 6.5-06. The rest of the case was left intact.
The 6.5mm-06 was finally accepted by SAMMI as the 6.5mm-06 A Square in 1997. The shoulder featured the same (or nearly identical) 17 degree angle as its parent case, the 30-06 Springfield.
While Europeans had been using the 6.5mm military inspired rounds for hunting and had expounded on its capabilities, acceptance in North America took a bit longer.
The 6.5mm cartridges are characterized by their long for diameter bullets that extend well into the throat. This gives them the weight necessary to carry their mass farther without increasing their sectional width.
the 6.5x55mm Swedish
What he created was the .263 Sabre.
The .263 Sabre differed from the 6mm-'06 and the .256 Newton in the shoulder. The Sabre had a sharp 35 degree shoulder where as the 6mm/'06 had a 17 degree shoulder angle and the .256 Newton had a 23 degree angle.
The 35 degree shoulder was probably a compromise between the 30-'06 which used a 17.5 degree and the Ackley Improved design which used a 40 degree shoulder. It said to provide a more positive head space adjustment over Ackley's design
Shannon named his new cartridge after the F-86 Sabre Jets that were stationed at McChord Air Force Base, near his home in Spanaway, Washington (near Tacoma). He said he would often see them flying overhead and when he created a cartridge that flew flat and true, he thought of the F-86.
Loading data for the more popular 6.5-06 can be used, but as always proceed with caution, start on the lower end and work your way up. Note the data published below was found online and I cannot vouch for its accuracy, use anything you find here or elsewhere at your own risk.
6.5mm-06
Introduced: 1913
Originator: Charles Newton
Other Names: 256/06, .256 Newton
Dimensional Data:
Bullet: .264
Neck: .300
Shoulder: .439
Base: .471
Rim: .473
Case Length: 2.50
Ctge Length: 2.80
Twist: 9-10
Loading data:
Bullet: Pwdr: Gn: MV: ME:
85gn H-414 55 3610 2461
100gn H4831 62 3445 2625
120gn H4831 58 3175 2680
140gn H4831 56 3000 2800
165gn H4831 54 2825 2922
Many have cautioned not to mix the 6.5-06 and the .256 Newton cartridges as the shoulder angle differences can cause head space issues. However I read of lots of people (including the owner of the rifle below) who reload using 6.5-'06 loading dies, then they fire form the cases to the chamber. Use extreme caution when doing this.
At the time of this writing you could purchase dies for the .263 Sabre from Midway USA, sadly the items were pulled, no doubt due to lack of sales. Your best bet would be to contact RCBS directly (I luckily thought to get a screen shot of the dies before Midway pulled them)
If you do intend to resize .30-'06 brass to a .256 Sabre, it is best to use Winchester-Western brass (WW head stamp). Jerry gave these instructions to his customers and several people have confirmed that WW brass works best. the reason for this is unknown to me, but it would seem that the necks are easier to size on the WW brass.
The gun in question here is owned by a friend. He bought it at a gun show in Puyallup WA, not far from Spanaway, where the gun was built.
The stock is a custom laminate using black walnut and maple, the bull barrel is 26" long and the action is a stretched M1903A3. Made longer to accept the 140 grain bullets, that when loaded in the .263 Sabre case exceed the length of the normal .30-'06 action.
The barrel has a rebated crown
Sources:
Gun Digest
American Rifleman
Chuck Hawks
Reloaders Nest
Ballistic Studies