doublegunshop.com - home Forums General Discussion Classic & Custom Single Barreled Sporting Rifles @ doublegunshop.com 1903 Springfield .25 Niedner/257 Roberts ?

chief al,
Don't worry,you can shoot the rifle.Try a 257Roberts cartridge, and if it chambers fire it.Be sure the rim is under the extractor, to hold it against the boltface.This case will then be fireformed to the chamber.If there is no problem with the fired case(excess expansion, splits,backed out primer, etc.),it can then be used to adjust the sizing die.Blacken the neck/shoulder with smoke/magic marker. Adjust the die to size the neck to just "kiss" the neck, and then either new or fired cases can be loaded with accepted loads. Have fun.BTW, if a cartridge , as advised above,will not chamber,set the shoulder of a case back a little at a time, until it will chamber.Lock the die there and load as above.You might have to shorten the die a little, and you won't be able to use factory ammo. Again, have fun.The dimensions you found with your new caliper are within normal tolerances, so there is no problem there.
Mike

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.257 Roberts (257 Roberts +P)

Back in the 1920's, N.H. (Ned) Roberts spent several years testing a number of .257" caliber wildcats on various cases. Probably upon suggestion of Charles Newton, Roberts finally settled on the 7 x 57mm Mauser case for his cartridge. Adolph Neidner built most of his test rifles, and Col. Townsend Whelen named the cartridge .25 Roberts. The final version of Roberts wildcat had an extremely long neck and mild shoulder angle. The cartridge quickly became quite popular and other firms such as Griffen & Howe and Sedgley chambered rifles for it.

In 1934, Remington simply necked down the 7 x 57mm case, retaining its original body taper and shoulder angle. About the only things the Roberts and Remington cartridges had in common were parent case and caliber. But, since Roberts had devoted so much of his life to his wildcat, it was only fitting that the new cartridge be called .257 Remington-Roberts.

Here is a drawing and measurements from COW for the .257 Roberts.

Thanks to everybody for all the helpful information and advice. I appreciate it and I will use the info and follow the advice.
Al.