257 Roberts Ackley Improved with 40 degree shoulder
He is my .250 Ackley Improved which was developed by Parker Otto Ackley, P.O. Ackley, was an American gunsmith, barrel maker, author, columnist, and wildcat cartridge developer, that sparked considerable interest in improved cartridges.
According to P.O. Ackley, the modified 257 Roberts was likely the best improved round compared with the couple dozen or so factory cartridges he’d experimented with.
The two most popular "Improved" .257 Roberts cartridges are the Ackley and RCBS versions. They are quite similar except for the shoulder angle, which is 40 degrees for the Ackley version and 28 degrees for the RCBS version.
The Ackley Improved family of wildcat cartridges are designed to be easily made by rechambering existing firearms, and fireforming the ammunition to decrease body taper and increase shoulder angle, resulting in a higher case capacity. P.O. Ackley improved not only standard cartridges, but also other popular wildcats. Measured water capacities of a standard .257 Roberts case and fireformed AI cases, the difference was about 13 percent (60 grains compared to 53 grains of water).
The Hornady Handbook and Nosler Reloading Guide show maximum reloads for the .257 Improved (either version) achieving muzzle velocities (MV) of about 3600 fps with a 75 grain bullet, 3400-3500 fps with an 85-87 grain bullet, 3200 fps with a 100 grain bullet, 2900-3000 fps with a 115-117 grain bullet, and 2900 fps with a 120 grain bullet.
The Hornady Handbook and Nosler Reloading Guide show maximum reloads for the .257 Improved (either version) achieve muzzle velocities (MV) of about 3600 fps with a 75 grain bullet, 3400-3500 fps with an 85-87 grain bullet, 3200 fps with a 100 grain bullet, 2900-3000 fps with a 115-117 grain bullet, and 2900 fps with a 120 grain bullet.
The fifth edition of the Noser Reloading Guide shows that 43.5 grains of RL19 powder can drive a 115 grain Nosler Partition bullet (BC .389, SD .249) in an Ackley Improved case to a MV of 2672 fps; 47.5 grains of RL19 will take the same bullet to a MV of 2960 fps.
The .257 Ackley Improved is a fine performer, adding up to 100 fps velocity over its factory cousin. One of its advantages, Ackley noted, is the fact that .257 Roberts factory ammunition can be used in an improved rifle if necessary.
Here is the FN 5.7×28mm (designated as the 5.7×28 by the C.I.P. and FN 5.7x28mm NATO) is a small-caliber, high-velocity, smokeless powder, rebated rim, bottlenecked centerfire cartridge designed for handgun and personal defense weapon (PDW) uses manufactured by FN Herstal. It is similar in length to the .22 WMR (5.7×27mm) and to some degree similar also to the .22 Hornet or .22 K-Hornet. Unlike many new cartridges, it has no parent case; the complete package was developed from scratch by FN.
The 5.7×28mm was developed in conjunction with the FN P90 PDW and FN Five-seven pistol in response to NATO requests for a replacement for the 9×19mm Parabellum cartridge. In 2002 and 2003, NATO conducted a series of tests with the intention of standardizing a PDW cartridge as a replacement for the 9×19mm Parabellum cartridge. The tests compared the relative merits of the 5.7×28mm cartridge and the 4.6×30mm cartridge, which was created by Heckler & Koch as a competitor to the 5.7×28mm. The NATO group subsequently recommended the 5.7×28mm cartridge, citing superior performance in testing, but the German delegation objected and the standardization process was halted until 2021 when it was officially adopted as a NATO standard STANAG 4509.
MkVII 303 for scale
Yes it may be an option to pull one of them but will wait for a while as I dislike pulling collected rounds apart.
my first photo shows both the 22 Hornet and the 22 K-Hornet developed by Lysle Kilbourn in 1940. Kilbourn opened the chamber making an improved version which is still in use today.
The 22 K-Hornet will fire a 35gr bullet at 3000 fps and a 50gr bullet at 2540 fps
My second photo shows a 5,56x33mm shortened case for use in smaller weapons, Some years ago IMI developed a short 5,56mm cartridge with a case length of 22.9mm and total overall of 30,15mm which fired a 46gr bullet at 1902 fps in modified UZI machine pistols. This cartridge is also known as the 223 Urban Cartridge, it is unknown if still in limited service.
India also adopted a new 5,56x33mm cartridge in the past few years too.
The other short cartridge in the second photo is the 30 Cal Kurtz which was developed by a private company to convert the M1 carbine. This also required a longer barrel and modifications to the carbine. The cartridge used 308 case cut down
and sized to use a 30 caliber bullet of 110 grs. It was not very popular and soon disappeared
Here my 256 Winchester Magnum
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The .256 Winchester Magnum is a firearms cartridge developed by Winchester, and was produced by necking-down a .357 Magnum cartridge to .257 diameter. It was designed for shooting small game and varmints. It is now obsolete and only offered by custom manufacturers
History
Introduced in 1960, Winchester offered ammo and reloading components into the early 1990s. The cartridge was first chambered in the Ruger Hawkeye single shot pistol. The next year (1962) Marlin chambered their Model 62 Levermatic rifle for the new Winchester cartridge. These were the two principal firearms chambered for the .256 Win. Mag.
Ballistics
From an 8.5 inch pistol barrel the 60 grain .256 Winchester factory load was advertised as having a MV of 2350 fps and ME of 735 ft. lbs. This was 250 fps faster and nearly twice as powerful as the .22 Remington Jet, a varmint cartridge for revolvers that was also based on a necked-down .357 Magnum case.
According to data from the fifth edition of the Hornady Handbook of Cartridge Reloading, hand loaders with a .256 rifle can approximately duplicate the Winchester factory load using the Hornady 60 grain Flat Point bullet in front of 15.5 grains of H4227 powder for a MV of 2700 fps. The trajectory of that load is: +2.3 inches at 50 yards, +4.4 inches at 100 yards, 0 at 200 yards, and -26.2 inches at 300 yards.
Winchester offered factory loaded .256 Magnum ammunition (and brass to reloaders) into the beginning of the 1990s. Winchester .256 factory loads used a 60 grain Open Point Expanding bullet at a MV of 2760 fps and ME of 1015 ft. lbs. from a 24-inch rifle barrel. That is about 500 fps faster than Winchester factory loads for the old .25-20 cartridge. At 200 yards the velocity was 1542 fps and the remaining energy was 317 ft. lbs.
Cartridges developed during the pre NATO 7,62mm period
I have a photo of three early cartridges that were tested before the 7,62x51mm was adopted.
On the left is one of my favorites, the 7x49mm Liviano, it originated from the FN factory in Belgium using an early US FATIEL 49mm case necked down to use the 7mm Mauser S12 bullet
with a velocity of 2750fps with a 140gr bullet. FN in Belgium sold 5000 FN FAL rifles in 1954 to Venezuela chambering this cartridge. Still in service until the early 1960's.
Second cartridge is the 7,92x40mm CETME from Spain for use in the German designed CETME rifle. It fired a 105gr aluminum core bullet at 2690fps. The aluminum core bullet could not be used as a military cartridge. The CETME used a reduced 7,62x51 loading until a stronger action was developed to use the NATO cartridge.
Last cartridge is also a favorite of mine, the 280/30 cartridge developed during the early post war period. It fired a 139gr bullet at 2500fps and would still make an excellent cartridge today
Been through my COTW 14th Ed scoured the net with different spelling and titles and drew a blank!!!!!
The cartridge was I.D'ed by the chap I brought the collection from as a 41 Patterson that's all the info I got.
Its parent case is an IMI 50 AE necked down to 41 cal with what appears to be a gas checked lead H.P.
So again RCS are you able to ID this thing correctly.
I am also unable to locate any information on the 41 Paterson cartridge. Looks to me as just a 429 Desert Eagle cartridge necked
down to 41 cal on the 50 AE case. There can not be that much improvement over the standard 429 DE cartridge and an expensive
project too
PM
