How to provide the best cases for a .257 Roberts?

Z

zeke mccune

Member
Hi Gang:

One of my next projects will be developing loads for a .257 Roberts. The gun is a 1952 F.N Mauser.

I may find some high quality 7 mm Mauser brass that I may neck down or perhaps there are other parent cases that I may use that are also high quality. Perhaps there is a soucce of high quality 6 mm Remington cases that I may use to form .257 Bob cases.

Any suggestions?

Tia,

Zeke
 
Picking one of these posts, I'm still a little confused. What do you mean by "best brass?" Most of us, building a custom, ideally start by buying 500 or so pieces of brass, and have the chamber reamer and sizing dies made based on that brass' dimensions. The cases last longer, and the rifle will likey be more accurate.

As you're starting with an existing chamber, probably one most of us would consider too large, I'd guess you're after (1) long life, and (2) even case wall thickness, esp. in the neck.

For the .257 Roberts, I would be tempted to try RWS 7mm Mauser cases. You probably have to get them from Canada. I've used them for a 6mm Rem AI.

The cost may be such that you could buy Winchester .257 Roberts P+ cases, measure them, esp. case wall runout, throw away half, and still be about even, without having to neck down a 7mm case to .257 and fireforming.

BTW, for .270 Winchester brass, you can get RWS, or try .280 Lapua & neck down (easy to do) & trim. I'd avoid .30/06 Lapua brass -- or almost any manufacture -- for some reason, .30/06 cases are rarely held to as tight a tolerance as the rest of the product line. Again, purchasing Winchester cases & measuring & culling may be just about as cost-effective.

If you don't load to higher pressures, Norma makes excellent brass. I don't mean low pressure, but for some reason, guys seem to like to push their loads to 60,000+ psi, rather than just start with a larger chambering. Some Norma brass is quite tough, but most assume you'll stay in the 55,000 psi region. And that's not CUP, but PSI. In other words, with high pressure, they don't last too long, even though Norma is generally the most dimentionally consistent brass.

Another thing: I was making cases for a 6.5x55 Ackley Improved Swede, and found the base diameter of Lapua to be fattest, Norma next, and RWS smallest. About .005 between Lapua and RWS -- see why it can be important to start a project with the brass in hand?
 
Hi to all who answered:

I have often thought that a factory barrel was a waste of time to attempt to make "good cases" for use as they would not respond to having the benefits of good brass. Then again, I have also wondered why if good brass worked well in a "match" grade rifle, would not good brass work well in a factory barrel and chamber. I have never seen any research to indicate that good brass was a benefit in any gun! Perhaps somebody who has the time and the means would do a research project to determine if indeed there was any statisical proof one way or another.

I was told several times in the past that a factory barrel would not be able to demonstrate any improvement when loaded with high quality benchrest grade bullets. Here again, I have not seen any proof to support this idea! Opininons are just worthless!

After thinking about the "best brass" question, I remember a quote fron the 50's about a gun question and the writer used term, "Like putting a Ferrari engine in a school bus." He was describing an idea that he thought was not too bright!

A
 
zeke mccune said:
.................................. I have never seen any research to indicate that good brass was a benefit in any gun! Perhaps somebody who has the time and the means would do a research project to determine if indeed there was any statisical proof one way or another.

I was told several times in the past that a factory barrel would not be able to demonstrate any improvement when loaded with high quality benchrest grade bullets. Here again, I have not seen any proof to support this idea! .............................Opininons are just worthless!

................................. Opininons are just worthless! ......................


A
Click to expand...

Yeahhh, well good luck in your quest.

All the best

al
 
some times lack of data is in fact proof........

those with the knowledge, are smart enought to not waste thier time....

does that mean a nice 30'06 wont shoot bib 187's...heck no.....but see how you do at a 1000 yds with that combo....

i shoot 135's( br bullets) in two factory rifles...one is a swiss k31 mil surplus...they shoot great and i have won matches with the combo...will those results stand up in a br match...heck no.
the other is an ar10(t) semi auto 7.62x51....and again shoots much better than milsurplus ammo, plus a winner again....but not like my br 308 win....heck no.

can you improve, sometimes yes, can you make a br gun out of a factory gun with br prepped brass...no.

mike in co
 
zeke mccune said:
Hi to all who answered:

I have often thought that a factory barrel was a waste of time to attempt to make "good cases" for use as they would not respond to having the benefits of good brass. Then again, I have also wondered why if good brass worked well in a "match" grade rifle, would not good brass work well in a factory barrel and chamber. I have never seen any research to indicate that good brass was a benefit in any gun! Perhaps somebody who has the time and the means would do a research project to determine if indeed there was any statisical proof one way or another.

I was told several times in the past that a factory barrel would not be able to demonstrate any improvement when loaded with high quality benchrest grade bullets. Here again, I have not seen any proof to support this idea! Opininons are just worthless!

After thinking about the "best brass" question, I remember a quote fron the 50's about a gun question and the writer used term, "Like putting a Ferrari engine in a school bus." He was describing an idea that he thought was not too bright!

A
Click to expand...

?? This post makes no sense to me. If you mean "no one has done the work to tell Zeke McCune what to order from the various suppliers," you're right. But there has been plenty of documented data both gathered and analyzed. Zeke -- and the rest of us -- just have to be ale to work from the general principles.

The "I've been told" is always worrisome. By Whom? Creighton Audette? Count on it. Mike in Colorado? Don't even listen (In passing, I'll take a .30/06 & 187 BIBs & get my share of wood at 1,000 yards. More wood in Highpower [see German Salazar's blog], less in benchrest, but that's due to the rules & the game.)

You talk of "factory" rifles as if they are one thing. The tolerances in the chamber -- the one area where "best brass" will help with -- are on a bell-shaped curve. Somewhere out there is a factory rifle where everything is perfect. But since there are 100,00 of them, good luck finding it.

The bell shaped curve applies to mach chambers too, it's just that the right arm is one hell of a lot shorter. Think it through.

Since accuracy seems to be your goal, remember the 1890s belief that no breachloader would ever be able to shoot with a muzzleloader. If you hedge your bet a bit -- most breachloaders won't shoot with most muzzleloaders, it would have been true. So, why is that, and what changed?

That's your answer.
 
A SAMI CHAMBER IS A SAMI CHAMBER!!! With the Roberts I had my best luck buying the Winchester, fireforming and then neck size only using the Lee collet die. Had two. One shot pretty good. One shot the big hole at a hundred. I have learned not to expect a Mule to be a racehores even if it is a damn good mule.
Tim Thompson
Hanover PA
 
LASER said:
A SAMI CHAMBER IS A SAMI CHAMBER!!!
Click to expand...

Really. Doesn't SA(A)MI allow tolerances? And are all SAAMI chambers perfectly centered on the bore? If so, case wall runout just became even more important, as now the brass could introduce an error not in the chamber.

But of course, they're not all perfectly centered in the bore.
 
Hey, since we all gotta' play nice now I guess EVER'BODY's right.... why bother? Opinions are all flawed, all are equally pertinent and facts can't be used for fear of hurting someone's feelings. My advice? Go ask this same question of every forum on the net.


Pick your poison.


Maybe over time we'll all be one BIG HAPPY forum, hopefully with government intercessors in place to keep it all civil, then you won't even have to shop around for opinions. It'll all be right there in one place.


wheee
al
 
Al, that's not true. There is plenty of hard data out there, an opinions that should not be ignored -- and by this, I mean the likes of Jim Border, Creighton Audette, Dave Tooley, etc. etc. You have to be able to take this general knowledge and apply it to your own situation.

If you take advantage of this, you will spend less money for a more accurate rifle.

If, on the other hand, you use the current rumor, fashion, whatever, seeking only brand names, you won't.
 
all
the reason for this is actually quite simple.
go look at the saami drawings for the chamber and the case.....
guess what.....it is an interference spec.
to stay away from this chambers are made to spec and brass is made at the other end of the brass spec...
i guess after 106 years its too late to fix the problem.
mike in co
Charles E said:
I'd avoid .30/06 Lapua brass -- or almost any manufacture -- for some reason, .30/06 cases are rarely held to as tight a tolerance as the rest of the product line. QUOTE]
Click to expand...
 
mike in col

See

http://en.wikipedia.org/wiki/Sporting_Arms_and_Ammunition_Manufacturers'_Institute

Under "Conflicting Industry Standards," follow the link to

http://en.wikipedia.org/wiki/Commission_Internationale_Permanente_pour_l'Epreuve_des_Armes_à_Feu_Portatives

The list of cartridges with differences (dimensionally) is quite large...

On the original (SAAMI) page, see also

http://en.wikipedia.org/wiki/Delta_L_problem

the .30/06 is hardly alone.

The problem I have with Lapua .30/06 cases is, if I hold "useable cases" to a wall variation of .004 -- which is generous, I perfer smaller -- I get about 50 pieces per 100 measured. Most everything else from Lapua I've measured gets you into the 90+ out of 100 pieces region.

Maybe I just hit a couple bad lots of Lapua .30/06, but I doubt it.
 
On a different note I'd suggest you have the .257 Roberts long throated an extra .15 or .2. This will provide some more boiler room for 4831 powder which can achieve remarkable velocities in the Roberts. This should work with your Mauser action. Keep in mind that much of the loading data you see if hamstrung because of the lower pressures available to certain rifles as well as the abnormally short throating in rifles like the 722 (short action) action. You'd be surprised what a case full of 4831 will do in a long throated rifle. Pressures will definitely be higher than the 45,000 S.A.A.M.I which no where near approaches the available strength of .257 cases.

Jerry
 
Charles E, you are dead nuts.

I would first want to know why a guy would want the "best" brass for a 257 Roberts and what his application is. Getting the best brass and putting it is a sloppy chamber is like wearing a three piece suit and wearing tennis shoes with holes in the toes.
 
Forming .257 Roberts from 7x57mm Mauser brass

(Does anyone mind much if I bump this old thread? There's already some pertinent content here to preface my question.)

According to Ken Howell in "Designing and Forming Custom Cartridges For Rifles and Handguns" the .257 Roberts can be formed from 7x57mm Mauser brass, as Ned Roberts did. However he does not specify "RCBS form die" as he usually does, but rather (by that omission) may mean a regular full-length .257 Roberts die will suffice for this process.

Further, I was surprised to find that, with all the form dies Huntington / RCBS list on their web page, there is no ".257 Roberts from 7x57 Mauser" die listed.

The question, then: Can the regular full-length .257 Roberts die properly reform 7x57mm brass?

(Please note: I am not asking for a recommendation for Roberts brass, or asking about the relative merits of reforming vs using manufactured Roberts brass. And no, I haven't called RCBS yet. I prefer to kick it around here first before working up the RCBS food chain.)
 
Forming brass

I formed 6 Remington brass straight from 7x57 Lapua brass, gave the mouth a hard chamfer, lubed with Lee White sizing wax, eased the handle down on the Full Length sizer, perfect cases.
 
keithcandler said:
I formed 6 Remington brass straight from 7x57 Lapua brass, gave the mouth a hard chamfer, lubed with Lee White sizing wax, eased the handle down on the Full Length sizer, perfect cases.
Click to expand...

Thanks! I have heard the "6mm Rem from .257 Roberts" forming is that easy, but everything I've read about "6mm Rem from 7x57mm" says necks will be too thick and need turning. Also, some had collapsed shoulders and felt a two-stage forming was warranted (e.g. down to .257 Roberts, or at least neck size down to .257 first.)

So the necks weren't too thick for your 6mm Rem chamber, and no "doughnut"?

Brian
 
Last edited by a moderator:
I have put Win or Rem 8x57mm brass in a 7x57 Wilson vise die, and from there into a 257 Roberts Wilson vise die.
No interference from a thick neck and shoots 1/2" 5 shot groups at 100m in a 257RAI on no wind days.

But if I neck down Norma 7x57mm rimmed to 257 Roberts and shoot it in the a chamber made with the same reamer as above, I get interference. The chamber neck is 0.288"
So I turn them on the lathe ala Mike Bryant.
The rimmed brass, which should be good for much higher pressure than rimless, is soft as butter and cannot even keep up with rimless.

And the same sort of thing happens when necking down 308 to 260. Different brands wind up with very different thicknesses. The chamber neck in 0.298" and 308 Lapua brass needs to be turned. 90% of Win does not.
 
You must log in or register to reply here.
Back
Top