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Old April 23, 2011, 12:17 PM   #1
rbursek
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257 Roberts overload

In modern bolt actions such as a Rem 700, Win 70 and a Ruger Hawkeye, how much over reloading maunuals Max loads for the +P can one safely load. I am debating between a 257R or a 257AI and wondering if the AI is worth the extra cost. I am not interested in the 2506at this point unless confinced otherwise.
TIA,
Bob
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Old April 23, 2011, 12:33 PM   #2
mikejonestkd
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+p is just that - over the standard pressure for a particular cartridge. If you exceed the +p loads for a cartridge you are potentially going to have issues with your rifle - such as a blown case, sticky bolt, stuck cartridges, or even a spontaneous rifle deconstruction issue.

For AI cartridges, there are several sources for loading info that will still be safe. If you need to load faster, then go to a bigger parent case.
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Old April 23, 2011, 12:54 PM   #3
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The simple answer is, you can't.


The more complete answer is, maybe you can't even safely reach "+p" loads in your rifle, with your choice of powders, cases, primers, bullets and final dimensions. Maybe you can exceed them safely, in your rifle, with your components. There's simply no way of "guessing" accurately. You'd need to test and you'd need to be well aware of pressure indicators and take careful measurements of a number of case dimensions.


I don't mean to sound like a jerk, I really don't, but if you have to ask the question, the answer is probably that you don't have enough experience that you should be concerning yourself with pushing load limits.

Besides which, maximum pressure and heat are two of the biggest factors in barrel life. If you really need to "push the envelope" with a chosen cartridge, the most logical answer is to step up to another cartridge that will do the job safely within published limits.
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Old April 23, 2011, 01:28 PM   #4
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got it!
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Old April 23, 2011, 02:52 PM   #5
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What pizzakilla said,kind of like if you want to hotrod a 44 spl,get a 44 mag.
I have owned a .257 AI for 20 years.I have some experience.
First question to ask yourself,what are you trying to accomplish?How far do you need to shoot?More velocity only potentially gives you a little more range.
The .257 R in original form is a fine deer hunting cartridge,period.You may not need more.There is +P brass,and there may be some +P data.In a modern rifle,it will be fine.Long ago,even 7x57 Rolling Blocks were converted,and load data is conservative for original performance .257 R.Its an old cartridge.
Another very important point.The screaming velocities of the AI hotrodder are achieved at +++++++P pressures.Fireforming that sexy shoulder does not make anything stronger.Loaded to the same AI hotrod pressures,a standard 257 would not give up so much.Getting the powder in the case may be the issue.
Consider,also,for the AI,you must load standard .257 R ammo,go to the range,and burn it to get brass for your AI.That takes 2 die sets,uses up some bbl,time,and money,and it is not your standard load,so sight in,etc is different.
I think very highly of my .257 AI.I accept the extra work and expense.I do not think any less of a standard 257 R.Wisconsin deer woods,standard .257 R,for sure.Western,wide open space pronghorn,coyote,mule deer....maybe,if you are a bit touched,quirky and eccentric,a .257 AI is very good,but don't push too far

Last edited by HiBC; April 23, 2011 at 02:59 PM.
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Old April 24, 2011, 09:01 AM   #6
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The standard pressure for Bob is about 45-48K psi(not CUP). +P was made to use the higher pressure found in most modern factory cartridges, about 60K psi.
The modern, bolt actions are safe at those pressures, as are AI cartridges...That will give you a margin of safety for variations in lots-of-powder, differences with your vs "their" scale, lots-of-primer, case manufactor, chamber tolerances, alignment of stars, etc.
The others are right...If you want a .257 that will step out well past what Bob does, get a Weatherby! (You said you didn't want a .25/06, lol.)
Have fun,
Gene
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Old April 24, 2011, 10:20 AM   #7
Jim Watson
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According to Speer No 12, which has the advantage of listing everything in CUP, the .257 Roberts is specified at 45,000 CUP, the +P at 50,000; the same as they use for .30-06. Later rounds like .243 are rated for 52,000 CUP which is about 4% higher. If you loaded .257 Roberts to that pressure, it would gain you MAYBE 2% higher velocity from 2% more powder. Hardly worth a jump into the unknown, but if you want to do it cautiously, you won't blow up the gun.

Note that the .257 Roberts was introduced in the Remington Model 30 which was also made for .270, then the hottest US cartridge. They sure weren't holding down pressures for that gun.
I doubt the legend that they were holding down the pressure for older custom guns. There WEREN'T ANY custom guns for .257 Roberts prior to its introduction by Remington.
The custom guns were for the original .25 Roberts made by necking down 7x57 brass with a 15 or 17 deg shoulder (Accounts vary, maybe the rifles did too, depending on who ground the reamer.) and trimmed 1/16". When Griffin & Howe started cataloging the caliber, they did not trim the length but maintained the shoulder angle.
The commercial .257 Remington Roberts retained the 20 deg shoulder angle of the 7x57 and its full case length.

So there were three versions, not two, and I doubt either .25 Roberts would accept .257 Roberts ammo. So new ammunition in old guns was not a consideration. Did Remington worry about new custom guns with their chamber in weak actions? It seems unlikely to me, in the era of Sedgley "re- heat treated" low number Springfields, Bannerman .30-06 Mosins, and other spooky combinations.

So, if you are so smart, why did they load .257 to lower pressure than .270 or .30-06? I think it was for accuracy. In those days the standard recommendation for improved accuracy was to load below maximum. And they were promoting the .257 as a deer and varmint caliber, so accuracy mattered.
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Old April 24, 2011, 10:49 AM   #8
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When I get 3900 fps with 75 gr Vmax out of my 257RAI, I know the brass is not going to last long. The primer pockets get loose.

If one backs off the same % safety margin from loose primer pockets in both 257RAI and 257R, they will find that the velocities are almost equal.

The notion that 257RAI is faster is just more load book baloney.
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Old April 25, 2011, 05:08 AM   #9
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I have no clue as to why the Bob was loaded so low...It makes no sense to ME. I have a Model 722 Remington that is no different I can detect from a 700, and that's plenty strong, in my book.
I've got a horror story about a Model 17 (not Bob) that indicates there were no weak rifles made for it. Some small-ring Mausers may have been rebarrelled to the .257 or maybe a 6mm Remington, but I'm not real sure that would be a bad thing, eventho' the safety-margin would be reduced from an M98.
The theory of going to less pressure for accuracy may have merit as the slowest powder at the time was equivalent to 4320, or 4064...both of which are good choices even now. The bullet loaded in Bob then was a round-nose so it was not intended for "long-range" in my book.
A lot of things don't make sense to me when we talk about the .257. Without reading the old books from the time, the .25 Roberts doesn't make any sense, but I have so I think the .257 is a nice little package. FWIW, I have an extended magazine in my M722 so I can seat pointed bullets to match the throat.
I don't KNOW which is better, CUP or psi, but as long as we use the same term and realize it's limitations, I think we'll be on the same page.
Have fun,
Gene
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Old April 25, 2011, 11:47 AM   #10
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Thanks for all your in put. I plan to go with just the 257R, and based on Hodgdon's 257 data and cup preasure, I should have no problems loading 115grain Noslers where I want to. Their cup pressures are about 46K, a regular Roberts is rated for about 45k and a +P at 50k. So in a Ruger Hawkeye 257R which I am assuming can handle the +P and a tich more, if case capacity is okay I should get close to the 257AI. My next thought is what is the cup pressure rating the manifactures make their actions to? Since many of the same actions are used for different calibers, with different max cup pressures. I see the 270win has loads for the 130gr that the cup preassure runs in the 60K range, so it the action is the same, the only difference is the barrel and chamber. Is that a safe analogy????
Bob
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Old April 25, 2011, 12:13 PM   #11
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If we were talking about an old action ,something like a Krag,action strength would be an issue.
The more modern bolt action designs,its less about action strength,and more about the pressure level the brass is designed to take.
The brass,not the action,is the weak link.(how well the brass is supported also matters).If the brass should fail,the hot,high pressure gas is a problem.
Not all brass is equal,and the various brass designs for different cartridges is a consideration in the max acceptable pressure.It is not necessarily a safe conclusion that because 270 or other cartridge is loaded to 60+ k that another cartridge would be safe.
Now,long ago I hot rodded my 257 AI with enthusiasm.I can say my primer pockets stayed tight till the necks split,but I was over any published load.At some point,better judgement kicked in.I opted for more margin of safety.I still get over 3000 with 115 gr bullets.
While the idea of "You never know what is enough till you find out what is too much" has merit,so does "No sense practicing something you can only screw up once"
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Old April 25, 2011, 12:20 PM   #12
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HiBC,
Thanks, I was not thinking the brass was the weak link, since it is incased in the chamber minus a .001 or so of being undersised at the time of firing. I have an AI now that has been giving to my son, and I guess I want another one for me without the added cost of a custom everything, so I was trying to see how far a regular 257R can be taken in a Ruger 77.
Thanks
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Old April 25, 2011, 12:47 PM   #13
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When you load to higher pressures over the published, very small things can and will create pressure spikes. without a ballistics lab to back you up in loading data your looking to get hurt.

Brass will flow like water at extreme pressures, high gas flowing back thru a action will cut flesh like a sharp knife.

As was said if you want high high performance --get a Weatherby 257
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Old April 25, 2011, 08:58 PM   #14
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Quote:
HiBC

Not all brass is equal,and the various brass designs for different cartridges is a consideration in the max acceptable pressure.It is not necessarily a safe conclusion that because 270 or other cartridge is loaded to 60+ k that another cartridge would be safe.
Do you know something I don't?
I have tested Win, Rem, and Lapua brass, and all the cartridges with the 1889 7.65x53mm Mauser case head, built with a large Boxer primer pocket have the same strength.

That list would include 22-250, 243, 6mm Rem, 250 Savage, 257 Roberts, 25-06, 260 Rem, 6.5x55 [US brass], 270, 7mm-08, 7x57mm, 280, 300Sav, 308, 7.62x51mm, 30-06, 8x57mm, 338F, 358, and 35W.

So far I have tested 22-250, 243, 250 Savage, 257 Roberts Ackley, 260 Rem, 6.5x55 [US brass], 270, , 7x57mm, 300Sav, 308, 7.62x51mm, 30-06, 8x57mm, and 35 Whelen.

I see the exact same Quickload pressure at the threshold of loose primer pocket, when I adjust the Quickload model for my batch of powder so the velocity prediction matches the chronograph. That pressure is ~ 74kpsi for loose primer pockets in one shot, and a little less for loose primer pockets in 5 shots.

I believe all those case heads are built the same.
They are all made of C26000 brass (cartridge brass) Temper - H06 Tensile yield strength - 65,300 psi.

There is a guy on the internet very handy with Von Mises calculations that says the yield should be at 77kpsi, which is not the same as Quickload 74kpsi, but maybe he is wrong, some assumptions are wrong, or QL is wrong or I don't operate QL correctly.
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Old April 26, 2011, 12:33 AM   #15
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"Note that the .257 Roberts was introduced in the Remington Model 30 which was also made for .270, then the hottest US cartridge. They sure weren't holding down pressures for that gun.
I doubt the legend that they were holding down the pressure for older custom guns. There WEREN'T ANY custom guns for .257 Roberts prior to its introduction by Remington."

A couple of points, if I may. For one thing, the .270 has been downloaded a bit since it's inception. That's because Remington saw fit to chamber their semi-auto rifle for the round.
Regarding custom guns for the .257, there were quite a few 1893 and 1895 Mausers that were made into very neat light weight sporters for the .257. These guns have alays been considered too weak for load much over 45K P.S.I or C.U.P if you prefer. back then both labels meant the same thing. It wasn't until they used transduceers that they found out different. Seems like some of those old mausers (1893) were converted to 7.62 NATO and were pressure tested and foung to be quite safe. I had a friend when I lived in San Francisco many years ago who just loved the 93 and 95 Mausers. He had them in the original 7x57 made into a sporter and made on in the .257 as well. I've always wondered in he ever made one into a 6MM Rem.
However, be that as it may, the pessure level for the .257 was deliberately kept low because of those older Mausers being rebarreled to the .257 AFTER it came out on the market. I never did ask my friend if he loaded his ammo hot.
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Old April 26, 2011, 06:59 AM   #16
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yes the 257 can be loaded to higher pressure then factory ammo. Thing is if you have to ask your not experinced enough of a handloader to be fooling around with doing it.
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Old April 26, 2011, 09:32 AM   #17
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How dead is dead?

My primary hunting rifle for deer and antelope is and has been a Model 70 Featherweight in 257 Roberts for the last 20 years. I don't think I've ever fired a factory round out of it.

Like most rifles I found that velocity in the Roberts does not mean accuracy. I've never seen a need either in hunting or accuracy a need to push this round to the max.

Probably the best deer size hunting round out there is the 243 Winchester. Compare the two, they are basically the same except you can get heavier bullets for the Roberts. Personally I use the 90-100 grn bullets and they have never failed me and I don't come close to HOT or MAX. When developing a load for the 257 or any other round, I start at the listed Accuracy Load, then tweak up or down until I find the load that fits my gun. I've never seen my load push the max limit.

Every one seems to ask HOW FAST can I make my load instead of HOW ACCURATE.
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Old April 26, 2011, 10:10 AM   #18
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Quote:
Originally Posted by kraigwy

Every one seems to ask HOW FAST can I make my load instead of HOW ACCURATE.
Like so many things in life, moderation on both counts. I don't see how it makes much sense to ask either question without the other.

What good would it be to have a load that prints 1/4 MOA if it has the trajectory of a 22LR? What good is "flat" shooting if it shoots 5 MOA?

Every cartridge is designed for a certain top end performance. If you can't get it, accurately, what's the point? If you get accuracy without using the cartridges energy potential, what's the point?

I don't see the sense in loading a 300, even 400, yard deer gun to 1/4MOA if I'm losing 300fps to do it when 1MOA would be entirely sufficient. Nor do I see the sense in gaining that 300fps if I can't hit my chosen target at sufficient range.
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Old April 26, 2011, 12:48 PM   #19
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I absolutely agree that a 2700-2800 fps .257 load will perform beautifully.The standard Roberts with safe loads is a fine cartridge.With my particular AI rifle,I found groups tightened up in the hot zone.Still,as I said,what seemed like a good idea 20 years ago does not seem like a good idea now.
Nothing ever went wrong,primer pockets stayed snug,a recheck of headspace after 8 lbs of powder though two rifles ,I could still just feel the go gage.All was working fine,but I backed off 2.5 gr of powder anyway .I gave up 100 fps.The margin of safety is worth it.
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Old April 26, 2011, 01:38 PM   #20
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Quote:
the pessure level for the .257 was deliberately kept low because of those older Mausers being rebarreled to the .257 AFTER it came out on the market.
That does not compute.
The .257 Remington Roberts was lightly loaded when it first came out before anybody got the dimensions and started using Spanish Mausers for .257 instead of .25. I doubt they held down the loads in anticipation of such guns.

Oh, well, ancient history now. The caliber is pretty much an Enthusiast Niche Round these days.

The class act in early days, after Winchester picked up the caliber, was to put a .30-06 follower and bolt stop in a .257 Model 70 so 100-117 gr spitzer bullets could be loaded long. This produced the "three inch Roberts." The next step was to throat the chamber a little longer to give the 3.3 inch Roberts.
We now know this did not increase case volume enough to make much difference, the shooters who went to that much trouble were also loading a good deal hotter.

Last edited by Jim Watson; April 26, 2011 at 01:43 PM.
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Old November 7, 2013, 10:10 AM   #21
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.257 AI

I have one of those .257 AI rifles and really like it. There are lots of .25 cal bullets out there and during our present ammo shortage craziness, when the shelves were empty of most other calibers, there were still plenty of .25 caliber bullets left.

I fire formed my cases using cast bullets so saved $ that way and the velocity gain does seem worth it.

I recently picked up a nice 6.5-06 and have put my .257 away for the time being but I am bringing it out of mothballs this weekend to try out some cast boolit loads again.

For some reason, the .25 isn't that common of a caliber although the .25-06 made it to the status of a factory round. I would not hesitate to tell someone interested in making up a .257 AI to go for it. It doesn't give up anything to the .25-06 from what I can see.
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Old November 7, 2013, 11:20 AM   #22
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"how much over reloading maunuals Max loads for the +P can one safely load."

When I was a young reloader in '65 one of our other young new guys asked the gun club's acknowledged 'Old Reloadin' Expert' - and he really was - basically the same question. Old dude looked at him a few moments and calmly answered to the effect that "Only you can find that out for your rifle and components. Start low and work up a quarter grain at a time until something blows; then back off a half grain ... or just stick with your book." It's still a valid thought provoking answer that I like to share from time to time.

Gun makers aren't stupid. If the simple change to an AI anything was worth doing they would have done it. If you need/want more quarter inch speed go to a .25-06; both it and the Roberts were once wildcats the factories jumped on.

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Old November 7, 2013, 12:12 PM   #23
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I don't think there's any "safe" loads over listed maximums stated in realistic loading data. Even +P loads are not "safe" in all firearms that can be chambered for them. Unless one has proper pressure measuring equipment, they're lacking the wherewithall to do that.

Cartridge brass typically starts extruding into chamber places where there's no support for the case at pressures starting at about 70,000 cup. I've shot dozens of 7.62 NATO proof loads in Garands and those cases look virtually identical to the same cases (by lot number) in its original M80 ball configuration; peak pressure from them's about 70,000 cup and then some.

In my opinion, far too many reloaders let their ego's take control over safety; sometimes out of ignorance and other times out of greed. If I were the moderator of this thread, I'd lock it up.
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Old November 7, 2013, 12:30 PM   #24
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Quote:
I am not interested in the 2506at this point unless confinced otherwise.
May I ask why aren't you interested in the .25-06 but want a 'souped up' .257 Roberts? The 25-06 has about a 200fps advantage over the .257 bob with equal weight bullets. Even with a +P or AI the 25-06 is still about 100fps faster than the 'souped up' .257 Roberts.
The pressure limit on the 25-06 is higher. And brass is probably easier to get being the 06' brass is extremely popular.
If you're just wanting something different, you could always go to the .25-06 AI which will be slightly faster.

I don't see the point in possibly having an unsafe load in a 'souped up' cartridge. When you can get something as available as the 25-06 which is even faster and more powerful, yet could be 'down loaded' to .257 Roberts +P or AI loads.
Just my opinion.
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Old November 7, 2013, 01:15 PM   #25
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Le me point out, gentlemen, that this thread was posted over 2 1/2 years ago and the OP has not been active in over 1 year.
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