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257 Roberts Improved 40 degree shoulder

10K views 20 replies 18 participants last post by  freefloater59 
#1 ·
I love 25 caliber guns. I am going to purchase a Ruger #1B in 257 Roberts and I am thinking of punching it to an Improved Does anyone out there know more about the improved and what i will gain by punching the New Roberts to 257 imp.
 
#2 ·
I have a improved 257, not quite a Roberts, but a 7x57 rimmed case blown out to just a little more than the Ackley version, which I believe may be near enough for me to comment.
To answer your question ... not a lot, as far as cleanly killing whatever you have your sights on. I had two standard 257Rbts rifles and then decided to make a bit of a wildcat version. I honestly cannot see much difference in the result. Everything seems to fall over dead just the same. I find the joy of owning something a bit different is the look on others faces when you tell them the calibre. Usually just a blank stare .... in the UK anyway.
I have settled on 51.5grns of H4831 / 100grn for my wildcat, which gives me 3180fps on average from a 16 1/2 inch barrel. That load shoots the tightest group for my barrel, but of course it is not recommended to start there with any rifle. Start down near 45 and work up watching closely for pressure signs.
I am also a great lover of the quarter inchers and particularly the Roberts version.
 
#3 ·
I reload for my Ruger Roberts.When I considered the AI improved conversion, these were my considerations:

The AI was never meant to make a cartridge like the 257 into a magnum. It will only increase the usable capacity about 3 grains of 4350. Increased velocity will be on the order of magnitude of 100 fps.

The AI designs in heavily sloped body cartridges like the 30-40 have certain advantages; no so for the 257 R.

The AI design was done by PO to reduce end bolt thrust, increase case life and to have something to write about. I like his writing and have all his books and many of his articles.

So I did NOT convert. I reload all my ammo for 40+ guns. So the reloading thing wasn't a negative. But my rifle is a Bicentennial model and the conversion would have cost me money to do and would only reduce the value of my gun on resale.

I agree with Sus, deer will never know the difference. "I honestly cannot see much difference in the result".

Just my thoughts.
 
#4 ·
Oldsouthpaw,

If ya want a AI, cartridge, go for it, but as had been said, don't expect great increases of velocity.

I had a 30/06 that I had rechambered to a 30 Gibbs, a conversion which increases powder capacity to a larger degree then the conversion to the AI chambers, say a change from the 30/06 to a 30/06AI.

This "06" was a slow rifle before the conversion, and even with a bunch more powder, it wasn't faster then a "fast" 30/06 after the increase.

Now, was it fun, you bet. Not everyone and his dog has a "Gibbs" chambered rifle.

Now, one thing to be aware of here. Make sure that anyone reaming a chamber to a AI chamber or any other conversion, does it properly. Meaning, an AI chamber should be reamed to allow a slight crush fit when a loaded standard factory - in your case - .257 Roberts case is chambered.

This will assure not having a head space problem and having properly fire formed brass.

It also allow use of standard factory ammo should the need arise.

When my rifle was rechamber to the 30 Gibbs, a true Wild Cat and not an "improved" cartridge such as the AI cartridges, the fellow ran the reamer in too deep, meaning that once the brass was fire formed, the neck was even shorter then that normally found on Gibbs cartridges.

Not a big thing considering the Gibbs requires case forming beyond that needed for a properly chambered AI chamber.

The AI cartridges look waaaay cool, and are great conversation pieces around the fire, but in reality there is not a great lot to be gained in the velocity department.

Crusty Deary Ol'Coot
 
#5 ·
Had a Ruger Ultralight chambered for the 257 AI. As above, got about 4 more grains of powder and a velocity increase in the neighborhood of 100 fps. Not much to brag about, but ..............

Case life increased dramatically with the headspacing on the sharper shoulder and straightened casewall. The 85 gr Nosler BT's and the 100 gr Hornady FBSP's with VithaVuori N135 powder were the most accurate loadings.
 
#6 ·
My standard chamber .257 Roberts has been very accurate, reliable, and predictable on deer and hogs. I think that's one of the charms.

Up to you, but I'd never bother. Not without trying the standard chamber first, anyway.
 
#7 ·
Thanks guys i have shot 250-3000 for years happened to pick up a set of 257 Roberts improved dies at Cabelos bargain cave a few years back cheap and just thought i would give it a try. Guess I will just keep it standard 257 Roberts I am sure it will be great
 
#8 ·
I have one currently and have had one other on a Ruger MKII. My current rifle is a Mauser '98 VZ24 action with a 24" tube.
The velocity gain is neither here nor there, IMHO, but if you want a bag of brass to last a looooong time, then this is for you. Both my 257 AI and my 22-250 AI will get 30+ loads through them with full power loads before I turf 'em. The other major advantage is that cases don't stretch and need trimming, if you're like me and hate trimming cases, then get your rifle rechambered by all means. Neck sizing only can last for 15 or so loads before you need to bump the shoulder back!
I have also found both rounds to be slightly more consistently accurate than the parent rounds and they are not finicky about brass, powder or bullets.

Cheers.
:D
 
#9 ·
CRF functioning

Magnum Maniac, How different does the 257 AI feed? You obviously have both numbers, so could you try one of each, slow and quick, and get back with any differences. I'm guessing that your rifle was tuned a bit for the A.I version, but that shouldn't negate using standard 257 Rem. Rob'ts ammunition.

I would note that the 257 Rem. Rob'ts, is NOT a 25 x 7mm Mauser. Neither are some 257 Roberts wildcats. I saw separated cases from a Wisner's made Mauser rifle, when the owner had his wife trying to use factory Remington ammo. I happened to be in the store when he came in all flustered. They had bins of brass, including some nickled 7mm Mauser brass there, so I merely pointed out the solution of doing it the old fashioned way, by necking down 7mm Mauser brass, just enough to chamber, and then setting his dies for that length. My understanding is that Ned Roberts did modify the shoulders of the military Mauser case for his true wildcat creation. For whatever reason, Remington made theirs a little shorter at the shoulders.

It's just a guess on my part, but I think part of Remington wanted their new 25 to be in a long action, and part of their management wanted it in the shorter, and more appropriate, 722 action. So they ended up with a long necked, 57mm long case with a 117 gr. bullet, deeply seated. I ran into this when I loaded for my 25 x 284Win. chambered in a Mark X Mauser action. It was a 55 mm case which kept any 57mm long Robert's out of the chamber, but mine could have used a longer throat, all the same. I.O.W.'s, one wildcat, one reamer, regardless of the receiver's magazine's length.

Someone at Remington did get over this particular hurdle, when they later came out with the 6.5 Rem. Magnum cartridge, which is also a 55 mm long case. Now if they had just left the belt off,-----.
 
#11 ·
Re: 257 ackley improved 40

Old southpaw;
I would shy away from converting the ruger. IMO it decreases the resale value. On the other hand, I own two and really like them . They kill no better than the standard Roberts,but are reloadable forever! A load of imr4350 puts three in 1/2 in. Groups. Hogs and deer have never a second shot.

Lester P
 
#12 ·
I will throw a "Wrench" into this discussion. I have owned 3 different 257 Roberts and have never had any success as far as accuracy with any of them A pre 64 Model 70 ,Remington 722 and Remington 700 Classic. I am a firm believer in the 250 AI and P.O stated that the 30-30 and 250 were two of his "Best" Improved cartridges.

The 250 AI will do anything the standard Roberts will and more accurately Sierra uses the 250 AI for all their accuracy/bullet load testing

Good Luck :)

Jim
 
#14 ·
Other considerations...

Old Southpaw,

I was considering having a sweet little Browning BLR rechambered to 257 AI a couple of years ago, and did a lot of research on the subject. All of the opinions stated here are valid. As many have implied, it just depends upon what means the most to you. I decided not to re-chamber, and here are the factors that influenced me, besides the fact that I would have ruined the resale value of my rifle. First, as several people have mentioned, not all AI conversions are equal, in terms of improved performance. The 250 Savage AI is one of the two best, with approximately a 17% increase in velocity. The improvement to the Roberts was meager, as several have pointed out. It was already a wildcat, and very efficient, before becoming standardized. Something that nobody else has mentioned is that SAAMI has increased the maximum pressure for the Roberts from 45000 CUP to 50000 CUP (referred to as a +P load, Winchester makes specific +P brass, but standard Remington brass has not exhibited any problems). THAT makes a substantial difference in the performance that can be wrung out of the standard Roberts cartridge. My BLR has a 22" barrel (from factory, long story). I have chronographed my 120 gr load at an average of just over 3000 FPS, and my 75 gr varmint load at an average of 3735 FPS, with no pressure signs, using Reloader 17 powder. That's some mighty snappy performance from what some consider an "obsolete" cartridge (My "Bob" has become my absolute favorite rifle). The Reloader 17 powder plays no small part. It is intended for use in smaller capacity cases, like the Roberts, and the short magnums. I have been playing with it quite a bit in my compact magnum cartridges too. It typically provides 150-200 FPS more velocity than any other powder that I have tried, with no pressure indications, and excellent consistency/accuracy. Loading data for Rel17 is still sparse. You will need to be creative and cautious in developing loads. Some of the more popular reloading manuals are now publishing +P data, and Rel17 data should become more widely available soon. I use the "Load From A Disk" software, along with other references, and am very conservative in developing a starting point for my test firing ladders. I echo the sentiments of most of the other people on this thread. Try your Roberts with standard or +P loads before modifying it. The 257 Roberts cartridge is a honey! If you do decide to rechamber your Ruger, be certain which reamer and dies you use. RCBS developed an "improved" version of the cartridge too, but it is their own configuration, not Ackley's, with a 28 degree shoulder instead of the 40 degree Ackley shoulder. Just be certain of which reamer and dies you are buying. Hope you enjoy your "Bob" as much as I do. (If you really want to play with an AI wildcat, take a look at what an "improved" cartridge does for the 250 Savage. It's impressive.)
 
#16 ·
Much of the "improvement" in the .250 Savage AI is just stepping on the throttle... the original .250 Savage wasn't loaded to very high pressures.

And having shot a few critters with the .250 Savage, it's more effective than folks would realize, as-is.
 
#17 ·
From the Sierra reloading manual, copyright 1978.

There are many "improved" versions of the 257 Roberts, with case shoulder angles from 28 to 40 degrees. We chose the version by P.O. Ackley because it was the "most" improved. We were very pleasantly surprised by both the velocity and the accuracy performance of this rifle-cartridge combination. At no time in the firing tests did we encounter erratic pressures, and the ballistic performance was very predictable. However, caution must be exercised when developing loads for this wildcat cartridge because of differenced in chambers, throats and bore sizes among rifles modified for it.
We consider the particular combination we tested to be ballistically superior to the 25-06 because the 257 Ackley Improved is about maximum case capacity for the .25 caliber bore.
The 257 Ackley Improved is both a varmint and big game round in one. As an added advantage, rifles chambered for it can fore factory 257 Roberts ammunition as well.


Test barrel length was 24" for the 257 Roberts AI
Test barrel length was 26" for the 25-06

117-120 grain bullets

257 AI, IMR 4831, 48.0 grains, 2900 fps
25-06, IMR 4831, 52.3 grains, 3000 fps

I quote this from Sierra as many may think that P.O. Ackley's data was biased.

Ackley cartridges typically give better brass life as the primary benefit from those who shoot them. Velocity increases vary from cartridge to cartridge based on the degree of "improvement" from the original. Case capacity increases are then capitalized upon if the cartridge is loaded to a higher pressure than the original offering.
 
#18 ·
rear locking actions

Mike G. I think part of this is that while the 250 Savage was chambered in their M-99 levers and 1920 rear locking bolts, the 257 Rob'ts wasn't. This is about half of the problem, IMO. IIRC, the 250 A.I. Savage is about the same capacity as the 25-308, or Paige Pooper. But it doesn't have enough neck to hold the longer bullets. The 257 Robert's is nicely balanced when used in a Mauser M 98 Action, including the Yugo 48's. I think that the Rem. 722, and its descendants like the Model 7 are a little too short for it.

So the 257 A.I. version would alibi those heavy bullets seated deeply into the cartridge case. I ran into this with my 25-284 chambered in a Mark X Mauser action. Plenty of magazine room, but too short of a throat. One wildcat, one reamer, so to speak.

Necking down a 7mm SAUM case would also short change a 25 caliber neck. Ditto for the 25 x 6.5 Rem Mag wildcat. But with a belt or a flanged rim case, there really isn't any shoulder datum point, to head space on anyway. So the 257 A.I. would seem to be pretty close to a stock 257 Robert's in a standard length action, like my Mark X. But for shooting over a bench at paper targets, the A.I. would sure earn its keep.
 
#21 ·
...my two cents worth, a few years ago I rebarreled my favorite Mauser 98 with a 24" in 257 AI 40deg version. Being a wildcatter and dedicated PO Ackley fan, i enjoy the loading and testing. I settled on a 100 gr bullet on top of 4350 at about 3300 fps for antelope, Texas whitetail, coyotes and other critters. Good accuracy, 1/2" three shots consistently but max pressure. Case life was 3 reloads. Great terminal results on everything hit. Loaded 120 gr at 3100 fps for mule deer, 400 yds shoulder shot proved to be max distance on the larger game, but still a one shot kill. Overall I like the 257 AI combination, especially with the 100 gr loads. Never had feed problems with the sharp shoulder in the Mauser. But I'm restless and will probably rebarrel for something else soon.
 
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