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subijitsu
04-25-2011, 9:41 PM
Howdy all. I have an old Mexican Mauser that my father gave me that has been chambered in .257 Roberts Improved. His uncle gave it to him when he turned 18 and my father in turn gave it to me. It has been sporterized by my great uncle, who was a hell of a gunsmith from what I hear, and it has a custom stock that my uncle made on it as well. Definitely a family heirloom that I would like to shoot eventually.

My father told me he installed the .257 barrel himself years ago. Not that I dont really trust my fathers work but I would like to check the headspace before I shoot it just to be sure. Unfortunately I have not been able to find a headspace gauge in 257 Roberts Improved. I can find 257 Roberts and 257 Roberts Ackley Improved at the standard places like Midway and Brownells.

From what I understand there are 3 variants of the 257 Roberts. 257 Roberts, 257 Roberts Improved (28 degree), and 257 Roberts Ackley Improved (40 degree). Of course I have the less popular version.

I would also like to reload this cartridge once I start shooting it as well but I think finding dies may be tricky.

Does anyone have any info on where I can find some 257 Robert Improved stuff? Or does anyone have some more info on this cartridge that I may need to know.

Thanks!

ElvenSoul
04-25-2011, 9:53 PM
Wow my uncle Orin swore the Roberts was the best gun ever made. You could kill everything that walks on land with one...was one of their selling mottoes. Loading is going to be a pain...due to powder and primer changes in the 70's these old guns aren't just the same anymore.

subijitsu
04-25-2011, 10:17 PM
Loading is going to be a pain...due to powder and primer changes in the 70's these old guns aren't just the same anymore.

Yeah, I think that I will be sticking with some pretty mild loads. Its just going to be an occasional casual shooter. No need for a hot 3000 fps 115 gr load at all.

The rifle was never even finished when I got it. The stock was only rough when my father got it, when I got it the stock was done but needed stain and finish so thats what I did. Also needs a scope mount installed and should probably should be reblued some time soon.

I will put up some pics tomorrow.

gunboat
04-25-2011, 10:51 PM
I think these are going to be a reload project -
There is likely no brass available so you will have to make cases from standard 257 by fireforming.
In an oversimplification, you use a low power load, seat the bullet touching the lands and set it off -- and bob's your uncle - you now have 257 improved cases - neck size only and reload from then on --
my ha-penny

subijitsu
04-26-2011, 6:59 AM
Thats basically what I was thinking. Do you think I can neck size with a standard 257 die or will I need an Improved die?

I also dont really want to shoot it untill I check the headspace so I will need to find a gauge before I fire anything. :(

I think these are going to be a reload project -
There is likely no brass available so you will have to make cases from standard 257 by fireforming.
In an oversimplification, you use a low power load, seat the bullet touching the lands and set it off -- and bob's your uncle - you now have 257 improved cases - neck size only and reload from then on --
my ha-penny

kendog4570
04-26-2011, 8:30 AM
The 257 Roberts and 257 Ackley Improved have the same shoulder datum, and use the same headspace dimension. This is true for most, if not all, of the Ackley Improved chambers. Not so with many other "improved" calibers. The shoulder angle is different, 21 deg for the 257 Roberts and its parent case the 7X57 Mauser, and 40 deg for the Ackley, but they headspace at the same point. Ackley designed them this way so one could use factory ammo in his chambers in a pinch. Your 28 deg shoulder might, as well. You may want to check with 257 SAAMI Go, No-Go, and Field gauges (also known as 7 Mauser) in your chamber and see what you find. Not the absolute answer, but if the gauges work (providing it was set up correctly originally) it might be OK. A chamber cast would be next.
If you are in the SF/Monterey Bay area I can help.

subijitsu
04-26-2011, 9:35 AM
The 257 Roberts and 257 Ackley Improved have the same shoulder datum, and use the same headspace dimension. This is true for most, if not all, of the Ackley Improved chambers. Not so with many other "improved" caibers. The shoulder angle is different, 21 deg for the 257 Roberts and its parent case the 7X57 Mauser, and 40 deg for the Ackley, but they headspace at the same point. Ackley designed them this way so one could use factory ammo in his chambers in a pinch. Your 28 deg shoulder might, as well. You may want to check with 257 SAAMI Go, No-Go, and Field gauges (also known as 7 Mauser) in your chamber and see what you find. Not the absolute answer, but if the gauges work (providing it was set up correctly originally) it might be OK. A chamber cast would be next.
If you are in the SF/Monterey Bay area I can help.

Very good info, thanks. That makes sense to me. I do know that you can use factory ammo in the Improved chamber as well and it will fire form.

I may have to pick up some 257 SAAMI gauges (providing the wife will release that much money to me) and see what I find. I would like to avoid a chamber cast as that sounds expensive. :lol: If i was in the Bay Area I would take you up on that offer, but I am north of Sac but thanks anyway.

kendog4570
04-26-2011, 9:47 AM
I do know that you can use factory ammo in the Improved chamber as well and it will fire form....

Thats a good sign right there.

subijitsu
04-26-2011, 9:54 AM
Here are some pics of the subject. I dont know what kind of wood my great uncle used to make the stock but it sure looks nice. It stained and finished pretty good too. I'm not a big fan of the shape but it is pretty darn comfortable. Sorry for the crappy pics.

http://www.calguns.net/calgunforum/attachment.php?attachmentid=95586&d=1303836623

http://www.calguns.net/calgunforum/attachment.php?attachmentid=95587&d=1303836637

http://www.calguns.net/calgunforum/attachment.php?attachmentid=95588&d=1303836648

ElvenSoul
04-26-2011, 11:53 AM
Glad your taking a old gun like this back to the firring line.

gunboat
04-26-2011, 1:53 PM
If you fireform cases, as I said, with the bullet touching lands you won't need to headspace the weapon. You are making cases to fit the chamber.
You should be able to neck size with a standard die -- I think lee makes neck size only dies as do others if you want to go that route.

I don't know abvout the headspacing of different 257 chambers, but I think a 7x57 headspace gage is the same as a standard 257rob -- I may stand corrected -

subijitsu
04-26-2011, 5:06 PM
If you fireform cases, as I said, with the bullet touching lands you won't need to headspace the weapon. You are making cases to fit the chamber.
You should be able to neck size with a standard die -- I think lee makes neck size only dies as do others if you want to go that route.

I don't know abvout the headspacing of different 257 chambers, but I think a 7x57 headspace gage is the same as a standard 257rob -- I may stand corrected -

Ok, but what if the headspace is off by a LOT while I am fireforming the casings? Even with factory or light loads couldnt this cause an unsafe condition? Or maybe crack the neck or shoulder of the case if there is too much space to fireform?

Also, I have never neck sized a casing before, but dont you need to full length resize after a few firings? Or will these casings not last that long since they have been fireformed to begin with thus shortening their life? I have heard that the 257 Improved casings dont last as long (due to the fireforming) unless you anneal them to help with resizing.

It would make sense that if the shoulder datum of all the 257 Roberts cartridges is the same I could use 257 SAAMI headspace gauges to check for safety, fireform my casings to my chamber, reload with neck sizing only, and shoot away. I hope.

I apologize for any dumb or tedious questions but I am anal when it comes to trying to understand these things. Until I wrap my mind around how it works I am lost.

Thanks for everyones help. :)

gunboat
04-26-2011, 5:55 PM
It almost does not matter what the headspace is when fireforming with a bullet touching the lands as the case is held against the bolt face -

the case would likely need full length sizing after a while - fl size, then form them again.

Case life would likely be shortened, annealing would help -

It sort of depends on how much you plan on using the weapon, 100 rounds a year no problem, 500 rounds may justify other loading methods.

my ha-penny

Riodog
04-26-2011, 6:25 PM
Give a call to RCBS and they can take care of you.
1-800-533-5000
or 1-916-533-5191.
They can answer all of your questions. Great people.
Rio

subijitsu
04-26-2011, 7:31 PM
It almost does not matter what the headspace is when fireforming with a bullet touching the lands as the case is held against the bolt face -

the case would likely need full length sizing after a while - fl size, then form them again.

Case life would likely be shortened, annealing would help -

It sort of depends on how much you plan on using the weapon, 100 rounds a year no problem, 500 rounds may justify other loading methods.

my ha-penny

Ah, I get it now. That makes sense. Load it to the lands to keep it against the bolt for the first firing and once the case is fireformed, good to go. I'm a little slow sometimes. :laugh:

I dont think I will shoot this rifle a whole lot. Maybe 100 rds a year once I get it dialed in with some good loads. I probably wont keep more than 2 or 3 boxes of handloads around at a time for it since it is more of a novelty than a workhorse. Unless it turns into my new favorite rifle. ;)

Thanks.

toby
04-26-2011, 8:22 PM
Load them up 10 or 20 at a time use a heavy bullet 115-120 grainers make sure to seat them touching tight to the lands and use a fast burning powder, like 4895 or so at a medium velocity not high and not the lowest. Remember to only do this for fire forming????? after fire forming load them off the lands...IMO, I have had the best luck using this method.

ElvenSoul
04-26-2011, 8:38 PM
This thread has got me wondering what became of my Uncle's 257Roberts...I know my Dad has his old 1903 Springfield.

kendog4570
04-27-2011, 2:41 PM
The 257 Roberts and 257 Ackley Improved have the same shoulder datum, and use the same headspace dimension. This is true for most, if not all, of the Ackley Improved chambers. Not so with many other "improved" calibers. The shoulder angle is different, 21 deg for the 257 Roberts and its parent case the 7X57 Mauser, and 40 deg for the Ackley, but they headspace at the same point. Ackley designed them this way so one could use factory ammo in his chambers in a pinch. Your 28 deg shoulder might, as well. You may want to check with 257 SAAMI Go, No-Go, and Field gauges (also known as 7 Mauser) in your chamber and see what you find. Not the absolute answer, but if the gauges work (providing it was set up correctly originally) it might be OK. A chamber cast would be next.
If you are in the SF/Monterey Bay area I can help.

I did a little more research, and I stand slightly corrected on the improved headspace measurement. See the attached pdf file by Ackley himself from the 1960's on headspace. He is one of the Granddaddys of the improved cartridge thing. The last few paragraphs shed some light on this subject of improved chambers. Also interesting is the rimless cartridge datum info. You could set a mike to the dimension, use the jaws to scribe a line on the shoulder of a factory case, do the same on a fire formed case, and compare the two.
Ackley was one of the greats. Just don't read his comments on the then-new .223 Remington, and the AR-15 rifle. Lets just say he is not one of our friends.

gunboat
04-27-2011, 11:40 PM
KD -- that is good info, what book is it from?

subijitsu
04-28-2011, 12:07 PM
Yes, good article indeed. Thank you. Mr Ackley may have known a little about the subject I guess. :laugh:

"Headspace for rimmed Improved cartridges, of course, is the same as for the standard versions but as a general rule for Improved rimless cartridges the headspace is .004 thousandths less than the standard minimum........The gauge for the Improved .257 would be 1.794 minus .004. This method is necessary because of variation in factory ammunition to ensure a crush fit at the conjunction of the shoulder and neck. This allows the fire forming of factory ammunition without loss of brass and with no danger to the shooter."

So what I am taking from this is that the chamber should be fairly tight with factory ammo before fireforming due to it being .004 under the minimum. So it would seem reasonable that if I were to buy factory ammo and it chambers a little tight I should be ok to fireform. If it chambers easily I may have an excessive headspace problem and need to buy new .257 brass, handload to the lands, and fireform from there. I can dig it.

kendog4570
04-28-2011, 8:17 PM
KD -- that is good info, what book is it from?

This particular article is in Gunsmith Kinks. PO Ackley used to have the gunsmith column in Guns & Ammo (I think, or Gun World) way back when (early 60's??). He wrote a lot of articles on this subject. Check out his double volume of wildcats for some interesting reading.

kendog4570
04-28-2011, 8:25 PM
Yes, good article indeed. Thank you. Mr Ackley may have known a little about the subject I guess. :laugh:

"Headspace for rimmed Improved cartridges, of course, is the same as for the standard versions but as a general rule for Improved rimless cartridges the headspace is .004 thousandths less than the standard minimum........The gauge for the Improved .257 would be 1.794 minus .004. This method is necessary because of variation in factory ammunition to ensure a crush fit at the conjunction of the shoulder and neck. This allows the fire forming of factory ammunition without loss of brass and with no danger to the shooter."

So what I am taking from this is that the chamber should be fairly tight with factory ammo before fireforming due to it being .004 under the minimum. So it would seem reasonable that if I were to buy factory ammo and it chambers a little tight I should be ok to fireform. If it chambers easily I may have an excessive headspace problem and need to buy new .257 brass, handload to the lands, and fireform from there. I can dig it.

Given this information, I would check the throat datum on both a factory case, and a fire formed case and go from there. .004" is probably no big deal with factory new ammo. It is made to fit in all chambers, min. and max., and even if it has little or no feel with yours, it will probably still be OK.
On the other hand, if you resize any case .004" under minimum, it will stretch and fail in short order with repeated sizing/firing cycles.
Gunboat nailed it, just set your die up for minimum, but adequate sizing, and enjoy the rifle.