257+p Roberts Hoax?

[workingman]

A few days ago I posted a question about whether to shoot 257+p in my 722 Remington. Everything should be fine was the general response. Dugout my reloading manuals, some old, some a little more modern. I just don't get it.
Loads from the Hornady 3 are hotter than the Hornady 4. The Hornady 4 manual shows using plus p brass. The Hornady 3 however does not. The older hornady does however show slightly longer col's. I really can't see any benefit here except you might use a little less powder. Velocities run the same in both books. It was basically the same in the Speer 12 and 13 manuals. Was this just a marketing ploy? Are you ramping up your 257+p beyond manual levels? I never have been about trying to eek out every last fps. But it seems to me it should offer something.

 

[Nullcone]

Somebody smarter than me can post the details, but I think two things are contributing here:

I'm guessing the transition from CUP to PSI as a standard occurred between Hornady 3 & 4. This lead to re-shooting of the test data at most if not all the big reloading concerns. Strain gauges/transducers (PSI) capture pressure data much more precisely that copper crushers (CUP)do... think of them as capturing something more akin to "area under a curve."

257 Roberts pressure standards (under both measurements) are notoriously low, supposedly to keep converted Mausers of a certain type safe. As to which, "small ring" and "Mexican" come to mind but please correct me if this is wrong. I believe the 257 pressure standard is the same as the 7x57 (parent case).

Also, see: 280 Remington/7mm Express for more pressure standad Shenanigans

hth

 

[Clark]

CAUTION: The following post includes loading data beyond currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The High Road, nor the staff of THR assume any liability for any damage or injury resulting from use of this information.

The 257 Roberts parent cartridge is the 7x57mm Mauser.
The first to be sold with this case head design was the 7.65x53mm Mauser.
The Mauser case head, when made with a Large Boxer primer pocket has an upper limit of ~65,000 psi for mass production in mass rifles, and an upper limit for handloading ~~ 70,000 psi for handloads for an individual rifle.

I use 257 Roberts brass or 7mm Mauser brass necked down or 8mm Mauser brass necked down in a 257 Roberts Ackley Improved rifle I built on a VZ24 action. I work up to loose primer pockets, and then back off 4% powder charge, and then put the load in Quickload, and voila .. 70k psi.

I started out reloading in ~ 1998 with a Rockchucker kit that came with Speer 12. I am still angry that I took that book seriously. I hate it when someone makes a fool out of me. AND I also went an entire season without realizing that Ice Road Truckers is scripted. How could I be so stupid?

 

[GooseGestapo]

The +P .257Roberts is the industry's way of getting around the original standard velocities/pressures of the .257Robt factory loads.

As reloaders, we've been using the more realistic pressure levels of the +P without even considering it as such.

Also, different component combinations and newer technology have influenced the data.

I had a Ruger M77MkII that was "maxed" out at the Speer data (ie:38.0gr of IMR3031 w/100gr bullet. Ditto 44.0gr of IMR4350). The pressures and velocities are predicated by the mfg's choice of components.

My circa 1983 M98 Custom sporter will take/handle loads in the Nosler #4 for the .257Robt Ackley Imp.

So, variations between guns/components is the reason for the sometimes "tepid" data for the Roberts. Like the .30/06 and others, so many guns have been built for so many years, you have to produce data/ammo for the most likely "lowest common denomiator".

Charley Sisk produced a rifle for one of the author/writers (Brian Pierce?) that was used to write an article for "Handloader" magazine. His rifle was a "short chambered" .257. His loads were way, way slower than the same powder charges (and no more accurate) than the two .257Roberts I owned at the time.
The .257Robt is my all-time favorite cartridge, but the rifles are what they are. Distinct individuals in many instances.
IMO the .257Robt +P was an honest attempt to "update" the cartridge in answer to pleas by some of the Writers and "churners" like us.