Not too much, you most likely do not have a benchrest 257 Roberts
Mine is an old Remington 722.
For serious hunting I would make up one box of like headstamps and load
it perfectly (scale) to know if I miss, it is MY FAULT
Mike
Not too much, you most likely do not have a benchrest 257 Roberts
Mine is an old Remington 722.
For serious hunting I would make up one box of like headstamps and load
it perfectly (scale) to know if I miss, it is MY FAULT
Mike
NRA Benefactor 2004 USAF RET 1971-95
Yes, it can matter a lot. Case capacity, head thickness, wall thinkness and case hardest need to be the same from shot to shot.Does it matter if the brass is mixed head stamp?
As I posted before, the 7mm Norma brass will be the most consistent and last the longest. After that, I'd choose Winchester.
Frank
I use PPU 7x57 brass and resize before first firing, after that neck size only. Works like a charm with minimal trimming. I shoot a custom M93 rebarelled to 257. Excellent accuracy and great on Texas and Arkansas white tail and hogs. Going to try my hand at varmints next
Since Privi now makes 6mm Remington brass, I would buy it and neck it up to the Roberts. Excellent affordable brass IME.
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I make 7mm Mauser Improved brass from 06 and 270 brass. Run it thru the die, then use a mini pipe cutter to shorten it before I trim it with a lee trim set up. Fire forming is needed to get the full Ackley size.
Wonder if you could do the same with 25-06 brass to get Roberts, sans the fire forming?
Reaming can be a pain, so if it were me and I could get 6mm. that is what I would do.
any time you are sizing the neck down to a smaller caliber, you end up with a thicker neck and it can raise pressures. If the neck holds a bullet after you fire form it, it needs to be reamed. This also can be from the neck being too long. I would try to find used .257 brass, places like American Reloading have new brass they have pulled the bullets from and you can buy new, primed brass cheap. If you size longer cases to 257, you probably will have to anneal and ream. Not sure the differences in 6mm, and 257, but if you are buying 6mm brass, you just as well buy 257
Neck reaming follows the easiest path and CAN lead to off-center necks if the case and reamer are not held true. RCBS makes a neck reamer die and cutter that hold tolerance. Neck turning provides a uniform neck wall thickness. Plenty of info on both on the long-range and precision shooting sites. A standard factory chamber will 'PROBABLY' take the necked-down 7X57 without problem. Sometimes a thicker neck on a case can improve accuracy.
Necking up the brass avoids all the silliness of reaming or turning. I have made 7 - 08 from .243, .358 from .308, and .250 Savage from 22 - 250 with no problems and no reaming and no turning. I mentioned the 6mm Privi brass because it is available now and 257 Roberts does not seem to be.
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I make 25-284 brass from 284. Similar sizing amounts, 7mm into 25 cal. I neck turn just because I have the gear and to hopefully increase accuracy, but the turning rarely takes off very much and isn't needed to fit the chamber. Same with my 25-270 that I make brass for from 270 and 30-06. I use nail polish in the base stamping to help distinguish the brass from the original caliber.
Kinda pricey but I just bought a new box of Nosler 257 Bob brass.
The fear of the Lord is the beginning of knowledge: but fools despise wisdom and instruction.
Proverbs 1:7
ammoseek and (sadly not so usable here) gunbot sometimes can help;
257 loaded rounds (hope you like 117 Gr bullets) for $1.34 {Hornady} - $1.45 {R-P} - I prefer 100 Gr. in Jacketed bullets but as my old R-P brass was getting old, got my good old woods partner new brass. Probably will go back to 100 Gr. bullets and change the scope to a better one & the mount to a non tip off one; Weaver K4 is a decent scope but my eyes are not as good as they were when I was 14 LOL
I could have reformed brass but already have 1000+ to form in other calibers, us old guys have to conserve energy some times
ive done it both ways. Ive never had a need to turn necks after using 757 and if using 6mm I make sure to lube the inside of the case neck. No need to remove the pin. Just run them through the 257 sizing die check the length to see if they need to be trimmed and if not just load them.
I’ll try that. Thanks!
Mauser 48 I sent you a PM.
Thomas
Last edited by Texas by God; 07-26-2018 at 07:06 PM.
BP | Bronze Point | IMR | Improved Military Rifle | PTD | Pointed |
BR | Bench Rest | M | Magnum | RN | Round Nose |
BT | Boat Tail | PL | Power-Lokt | SP | Soft Point |
C | Compressed Charge | PR | Primer | SPCL | Soft Point "Core-Lokt" |
HP | Hollow Point | PSPCL | Pointed Soft Point "Core Lokt" | C.O.L. | Cartridge Overall Length |
PSP | Pointed Soft Point | Spz | Spitzer Point | SBT | Spitzer Boat Tail |
LRN | Lead Round Nose | LWC | Lead Wad Cutter | LSWC | Lead Semi Wad Cutter |
GC | Gas Check |