What parent cartridge was used to create this 401 slr


It is the same size as the WRA co factory 401 cartridge but it’s marked RA 58 with a circle/cross symbol. I’ve got others marked RA 60 all in a box marked .401. From what I’ve learned here and on the web I’m thinking the RA is for Remington Arms and the 58 is the year manufactured and that these are used on military cartridges. Since the 401 wasn’t a military cartridge in 1958, was this case made from something like a .308? Now the .308 is not one of the cartridges recommended to use to make a .401. Usually it’s the 30-30, 35 Remington or 7.62x39. What do the members think?





You are correct as to the parent case ID. If the external dimensions are a good match, the question would be the material remaining for suitable case strength. If you were to weigh an original .401 SL case vs. your home brewed item there may be a clue to be found.



It would be difficult to convert the .308/7.62 or .similar cases to .401 as the base diameter of the latter is .429, while the .308/7.62 case is .473. I suppose it could be done but it would take a heavy swaging press and reaming of the case. With the military headstamp with the circle-cross NATO stamp, yours would have to be made from a 7.62 NATO case.

There are very few readily available cartridge cases suitable for re-forming to .401 WSL, but the .30-30 could probably be made to work, despite its smaller base (.422) and body diameter. But it would be a job requiring an intermediate fire forming operation. I form .303 Savage cases from .30-30 brass, and the .303 Savage has a .427 base diameter. It works as the first shot fire-forms the body. I centralize the case with tape prior to firing.


From what I’m reading here then is someone made these 401 cases to specification from 7.62 nato cartridge? Man they must have been desperate.

As far as weight a WRA Co case weighs 117.1 gn and a 7.62 convert weighs 152.2 gn.


The high weight of the .401 case formed from the 7.62 suggests that the reduction in diameter was achieved by swaging the case down to .401 size. The rim was left nearly as original, merely reducing it a bit to match the .401. I assume when you reduce a case this much it is then necessary to ream the primer pocket back out to correct diameter? Jack


The 7.62 primer pocket would probably not be affected by a base swaging operation, but if so, it could be easily reamed to proper dimensions. But the shortened case mouth would probably have a case wall too thick and would also require reaming to thin it. Donnelley’s manual recommends forming .401 starting with a 9.3x72R case, but I don’t know where one might find those. Maybe Norma??


Last time I looked, Sellier & Bellot made 9,3x72R cases as well as a small German shop called Horneber.


If there is a difficult & expensive way to form an unusual case, Donnelly seems to prefer it. I have one of those old .401 WSL rifles. The easy way to make usable cases is to expand 7.62x39 cases with a stepped 9 mm & 10 mm expander. What was the parent case for the 7.62x39?


7.35mm Carcano and 6.5mm Carcano.