Thread: 257R Experiences

Originally Posted by tetawa

loaded up using R-P new brass, numerous misfires with poor primer strike, no problem with Norma ex 7x57 cases, checking brass the R-P has a much wider extractor groove, remember many moons ago having or hearing about a similar problem with 257 brass but can't remember exactly.

Greetings @tetawa,
The problem was likely that the R-P brass was shorter to the shoulder than Norma. The yanks, being what they are came up with a different chamber than the Mauser standard in the days before SAAMI. so SAAMI dimension cases will be short in the Mauser chamber, Having done this the US rifle manufacturers had to cut the chambers long enough to accept the continental round. This was well covered in a recent rifle or handloader and from my experience happened with the the 6.5x55 and likely others as well. Get yourself a headspace comparator tool from Hornady and do some measuring.
GPM.