Thread: 257R Experiences

The 100 gn Hornady and Speers were about 100 fps slower. 40 degree ai chamber.




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Originally Posted by Dicko

The 100 gn Hornady and Speers were about 100 fps slower. 40 degree ai chamber.




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Have a few pkts of Nosler 100 BT and a pkt of 100 Partisan's, my last Ackley ran on the old Nosler 100gr Solid Base with H4831, the old reclaimed version.

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.

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.

in theory, because it headspaces off the shoulder..the size of extractor groove SHOULDNT come into play at all....be interesting to find out what is going on.

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.

Did you seat well out to get bullet jam for fireforming? This really helps eliminate light strike issue.

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Originally Posted by Mathias

Did you seat well out to get bullet jam for fireforming? This really helps eliminate light strike issue.

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Yes, 117 RN way out to get jam. Barely marking the cases, with ex Norma 7x57 great strike. same primers. Have primed and fired both with m't brass, no problems with the ex 7x57. Will put up photo tomorrow showing the difference in extractor grooves.

Originally Posted by tetawa

Yes, 117 RN way out to get jam. Barely marking the cases, with ex Norma 7x57 great strike. same primers. Have primed and fired both with m't brass, no problems with the ex 7x57. Will put up photo tomorrow showing the difference in extractor grooves.

I had a similar problem with my 260 improved and found if I gently closed the action on the round rather than normal speed, I had a higher success rate. Shutting too fast pushed the projectile into case & I got less headspace jam & a weak strike


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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.

An interesting scan through this thread, I've had a .257R as my go to for best part of 40years now, a Medium Action BSA Hunter with a worn out 7x57 tube, Din Collings rebarreled it into 257x57 with a slim 22" Douglas barrel. I asked him to throat it to allow for seating 120 grainers right out to mag max, ie 3", he erred on the generous side & I ended up with a bit more free bore than I'd reckoned on but the plus side was I found I could use 257 Improved data pretty much. I've recently bought some 110 gr Hornady ELD-Xs to have a play but in real terms, I've enough 120 Speers & Nosler SBs to see me out I reckon. I haven't shot anything but paper with it for years but prior to that it did all I asked of it.

I use a starting load with a 87 gn pill to fire form cases. They are quite accurate for game or paper.
After fire forming I reckon you should anneal them as they tend to get brittle necks a bit quicker than non ff cases in my mind.

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Have more brass from different manufacturers on the way, will report back after further trials.

Well, had a thought, neck sized up to 270, then resized to 257 creating a false shoulder, bingo all sorted.

Originally Posted by tetawa

Well, had a thought, neck sized up to 270, then resized to 257 creating a false shoulder, bingo all sorted.

Yes that's what I did with a 6.5x57AI

Starting load, light pill, seated into the lands.


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Originally Posted by Dicko

Starting load, light pill, seated into the lands.


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Still getting 40% failure using 95 Berger and the RP brass, will find something lighter? No problems with WW and Norma brass, ex 6mm