+P loads

[Jim Watson]

The history I have seen does not support the use of the .257 Remington Roberts cartridge in wildcat form. It was brand new in 1934. The original .25 Roberts wildcat(s) is not the same.
Therefore it does not have the same manufacturing history as the .35 Whelen or other Remington commercializations like .25-06, .22-250, or .260.
More like the .280 Remington, which is not a commercialization of 7mm '06, either.

 

[Blue68f100]

The +P designates it running over spec design pressure. The rating does not always mean higher velocity. In many case higher velocities can be reached with std pressure ratings with the right powder.

Like most of us who started many many decades ago we worked up loads that are now considered over pressure. I personally still use them today and don't plan to stop any time soon. I have got to the age now where I don't care to beat my self up with super hot loads. I see no need when just punching paper.

 

[Slamfire]

The history I have seen does not support the use of the .257 Remington Roberts cartridge in wildcat form. It was brand new in 1934. The original .25 Roberts wildcat(s) is not the same.
Therefore it does not have the same manufacturing history as the .35 Whelen or other Remington commercializations like .25-06, .22-250, or .260.
More like the .280 Remington, which is not a commercialization of 7mm '06, either.

Until someone contacts SAAMI and researches the minutes of the meeting where the original 257 Roberts pressure requirements were set, all we can do is make assumptions. The round was certainly handicapped by a 45,000 cup upper limit, but not too badly, the Army 30-06 had a 50,000 cup upper limit. I prefer to infer that the standard was based on the actions available in the 1920's, which would have included low number Springfields in the mix.

Is not the current 8mm Mauser SAAMI pressure 35,000 psia? Because America does not require firearms to under a proof, each and every time the firearm is sold, such as the Europeans do, ammunition manufacturers have a lot of uncertainty about the quality and structural integrity of the used firearms on the US market.

 

[Jim Watson]

Well, it looks like we need old Remington files or a good medium to learn why the .257 was underloaded.

I note that it has a slightly lower CUP MAP than its parent 7x57, the 6.5x55 meant for small ring Mausers and Krag Jorgensens, and much less than its predecessor, the .270 which was equally exposed to low number Springfields, and the same as .250 and .300 Savage which were made for a lever action.

I prefer not to infer that the Remington was so considerate of the gunsmith and shooter as to look out for them this one time. I mean, after all, they made High Velocity .44-40s that were hazardous to your Colt if you ignored the label.

The 8mm is a different case. The 8mm Remington Special was apparently made to protect their customers from surplus 1888s. It was standardized by SAAMI without the two tier approach of the Germans who well knew the difference between the "I" and "S". Haven't been many American made 8mms in the face of the tidal wave of surplus from Europe after two losing wars for the Germans. So SAAMI and Remington had no interest in making cheap foreign stuff look good.

 

[Slamfire]

I prefer not to infer that the Remington was so considerate of the gunsmith and shooter as to look out for them this one time. I mean, after all, they made High Velocity .44-40s that were hazardous to your Colt if you ignored the label.

Every time a panel meets with even one new person in attendance, the dynamics and the decisions will be difference from the last, and the next.

 

[Jim Watson]

True. Was U.M.C. Thomas still there in the 1930s? Google does not know him and I no longer have the Gun Digest/Handloaders Digest with the long article about him. He would have gotten it right.

 

[someguy2800]

The answer to all these questions are "we guessed".

 

[Jim Watson]

Pretty much. Dang those people for not posting their thoughts on Facebook.

 

[Demi-human]

I always thought that the extra pressure would be good for guns that may be a bit finicky in the break in, or for positive function in the most extreme of conditions or concealment. (Knowing more pressure does not always equal increased performance.)

While most of my handguns are rated for "plus pressures" I have not loaded above what I have found listed in the major distributors of loading information. Although I am guilty of looking for the higher loadings listed among them.