257 Roberts brass question

[gunjnkie]

Anyone here reload 257 Roberts? I've purchased a Savage 111 that I'm going to rebarrel to 257 Roberts for my children to target shoot/hunt with. I purchased some Winchester +P brass the other day. Up until now, I have not sorted brass by weight etc because I just like to go out and shoot. However, after I've been doing some reading on different forums and such, I decided to measure and weigh 10 random pieces of the brass from a bag of 50. Weight varied 2.6 grains (173.8 to 176.4), length only varied about 0.001". What bothers me about this brass is that the rim and head only measure 0.466". All of my loading books and reference diagrams that I have on the 257 Bob state a rim of 0.473" and head of 0.472". Now that's a difference of only 0.006" to 0.007" , but is this something that I should be concerned about? I don't have a ball micrometer yet to check the necks, but that is coming in about 6 to 8 weeks.

Does anyone use the Remington brass for the 257 Bob? What do your cases measure?

Any advice or comments would be appreciated.

Thanks, John

[gotcha]

just measured 10 of my Rem. standard .257 rob. cases. They averaged .468" rim dia. & .467" @ the web. (these are not +P ) I've always opted for standard brass for the potentially larger case capacity. Can't offer any opinions on the +P variety diminsions. Do your calipers measure accurately in the .300" to.600" range? Try checking a known dia. like a bullet. I neck size only as I'm shooting a .257AI single shot. Your case life might suffer a little if you are full length sizing, but this would be true of any case/brass that is being F/l sized. Hope this helps. Anybody have input on case dimensions VS chamber reamer specs. ?

[gunjnkie]

Thanks gotcha! I too would be interested if anyone has any info about the case dimensions -vs- chamber specs. I may have to email PTG and see if I can get drawings for their chamber reamers.

[Eric in NC]

You will find almost all factory brass is undersized - bolt heads are generally oversized (contributing to the famous Savage ejection problems).

I don't think there is ANY difference in +P and non +P 257 brass - just in the load that the factory puts out.

[gotcha]

Hi Ya' John, I agree w/Eric on chamber dimensions vs.actual cartridge dimensions. Actual cartridge dimensions from factory will run smaller than measurements shown in R/L manuals. Most R/l mans. show actual saami REAMER dimensions rather than real world cartridge dimensions. Saami has recently deleted its standard cartridge dimensions from its web site. I measured 10 rounds of rem.7mmX57 brass (unfired, which is parent cartridge for .257bob) found it very close to meas. of .257bob in my first post. Some of these had .466" rim dia. Also measured some 7mmX57 Norma I had on hand. rim dia. ran from .467" to .470" and webs ran from.465" to .469". Rem. brass nk. wall ran .0125" to .015"+ and norma nk. wall ran a pretty consistant .016". Now, about +P brass. Check this out: www.chuckhawks.com/sensible_cartridge.htm Seems that .257bob +P is thicker! At least Winchester is. I'm sure you could contact customer svs. for r/l manual/manuals you use and get clarification of dimensions they publish as cartridge specs. As an example 6mm ppc has about 8 or nine reamer specs. depending on manufacturer. Long story short, shoot your brass but start LOW w/powder chg. & watch for flattened primers. Yer good ta go. Dale