Help Understanding Max Loads for .257 Roberts?

[Vartarg]

I bought some 100gr Partitions to load for my .257 Roberts....I plan on hog hunting in a couple of weeks in Texas. The max load in the Nosler #6 manual is 40.5gr, and on Hodgdon's online data website, the starting load is 40.5gr and the max load is 44.0gr. Why the disparity?

Thanks in advance.....

George

 

[DrMike]

Vartag,

Welcome to the forum. I take it you are asking about H380? Is that correct? Differing conditions, differing lot numbers, differing primers, etc. give slightly differing charges to reach maximum. In the case of the Nosler Guide, you are given data for either a 100 grain Ballistic Tip or a 100 grain Partition. The Hodgdon data is given for a 100 grain Speer SPBT. The difference in bearing surface will account for much of the difference in pressure generated.

 

[Vartarg]

Thanks....it dawned on me a few minutes ago that I'd left out the powder...yes, it's H380.

I appreciate the response......

I realize the bullets are different designs by different manufacturers.....but that still strikes me as a pretty large differential....not explained by bearing surfaces or powder lots. JMHO.

 

[JD338]

Varturg,

Welcome to the forum.

DrMike nailed it.
I load my 257 Roberts with 100 gr BT/PT bullets and IMR 4350. My load is above Nosler's published load data but it is safe in my rifle. MV is 3000 fps and it shoots .5 MOA from a M700 Classic.

The 100 gr PT works very well from the 257 Roberts.

JD338

 

[Ridge_Runner]

here is what I found, it was either alot of reading for you or alot of typeing for me, was a no brainer
http://www.ballisticstudies.com/Knowled ... berts.html

.257 Roberts
History

The history of the .257 Roberts dates back to the 1920's, when a wildcatter by the name of Ned Roberts began to experiment with the .257” caliber. It has been suggested that Charles Newton persuaded Roberts to settle on the 7x57 case design and that close friend Col. Townsend Whelen suggested a 15 degree shoulder. Unfortunately, exact details of the time are sketchy. What is known however, is that Roberts did indeed adopt the 7x57 case, changed the shoulder angle to a gentle 15 degrees and opted for an extremely long neck. Townsend Whelan apparently named the new cartridge the .25 Roberts and Adolph Niedner built the first rifles in 1928.

Following its release, the Remington Arms company saw great potential in the .25 Roberts. Remington utilized the basic concept of a .25-7x57 but chose to simply neck down the 7x57 case with no other change. Since Roberts had devoted so much of his time developing the cartridge, Remington, out of respect, named it the .257 Roberts.

Officially released to mainstream hunters in 1934, Remington initially made a poor decision, loading the Roberts with a 117 grain Round Nose bullet. The Model 30 rifle that housed the Roberts had a short magazine and with the 117 grain bullet, powder space was badly cramped giving poor velocities in the order of 2650fps. In this configuration, the Roberts offered nothing over the .250-3000. Hunters who were absolutely keen on the Roberts either modified .257 rifle magazines or built custom rifles to allow bullets to be seated out where they belonged. Set up this way and using hand loads, the Roberts was able to fire a 100 grain bullet at 3000fps and a 117 grain Spitzer at 2800fps. Nevertheless, for the majority of hunters, especially those outside of the U.S, the Roberts was viewed as a bad idea. The Roberts was thrown even further into decline when Winchester released the .243 in 1955.

Popularity of the .257 Roberts has remained static since its introduction. Only a few hunters use this cartridge and those who do, generally favor it for reasons of low recoil versus adequate killing power on certain game species. From time to time, various gun writers have written enthusiastic articles about the almost forgotten cartridge while in a similar fashion, gun makers have produced limited runs of .257 Roberts caliber rifles.

During the late 1980s, Winchester re-introduced the .257 Roberts into the Model 70 XTR line of rifles. In this case, the Roberts was housed in a long action, long magazine rifle offering reloaders plenty of flexibility. Ironically, a great many of these rifles were reamed out to the more potent .25-06 to fully optimize the long actions.


Performance

Generally speaking, high velocity small bore bullets kill much faster than low velocity small bore loads. So long as penetration is adequate, a 100 grain bullet driven from the Roberts at 3000fps produces fast kills on medium game and is noticeably faster killing than a heavier counterpart at ranges beyond 150 yards.

The theoretical advantage of the Roberts is that it can fire a 120 grain bullet to give a balance of deep penetration combined with low recoil. It must however be noted that this is a modern concept and not the original design premise. Had Ned Roberts been able to take advantage of slow burning powders, he most likely would have adopted the .30-06 case to maximize velocity, wounding and fast killing. In truth, Roberts was to a great extent, attempting to improve the .250-3000.

The 120 grain load is certainly capable of relatively deep penetration without need of premium bullet design. That said, loads driven at 2650fps are best utilized for close ranges, as beyond 100 yards, kills can be very slow. Only 117-120 grain loads travelling at or above 2800fps can be considered useful for longer ranges.

The difficulty with the 120 grain bullet driven at 2800fps is learning how to utilize such a load without sacrificing speed of killing. The main factor, is of course, shot placement. The hunter must always try to break foreleg bones of medium game in order to maximize bullet expansion, wound trauma and also, destroy the autonomous plexus hidden between the scapula ball joints. As a refresher, the heaviest bones of the foreleg intersect at the scapula ball joint slightly forwards of the apparent vertical line of the leg viewed broadside. In other words, the hunter needs to place shots approximately 1” forwards of the foreleg, rather than the natural tendency to use the line of the leg as the point of aim.

The forwards shot at close to moderate ranges is pretty easy. The greater difficulty is maintaining the discipline to not aim behind the shoulder at longer ranges. On a calm day, such shot placement can be mastered quickly but in crosswinds, long range shot placement can become very difficult.

Slow killing rear lung or neck shots at ranges beyond 250 yards have turned many hunters away from mild velocity small bore loads. It cannot be re-iterated enough that regardless of meat damage, breaking major bones, destroying the autonomous plexus and forward lungs are keys to consistent performance in the Roberts.

The .257 Roberts is a low recoiling, mild powered cartridge. In a short action, it has the potential for a suitable youth rifle but lacks the power with many 117 to 120 grain loads to be of any great advantage over the more common .243. The Roberts gives much better performance when hand loaded to suit a long action rifle but such rifles are often too heavy for youths. Contradictions like these have always plagued this cartridge and in truth, the Roberts is best housed in a long action and best suited to adults or late teenagers who, for whatever reason, are unable to tolerate recoil.


Factory ammunition

With modern powders, factory ammunition makers are now able to produce full powered .257 Roberts ammunition without need of a long cartridge over all length (COL). That said, factory ammunition for the Roberts is not a common sight on gun store shelves anymore and outside of the U.S, is available only by special order.

Strangely, the only manufacturer to continue producing low powered loads for the .257 Roberts is the Remington. This company currently produce a single load for the Roberts, the 117 grain Core-Lokt at 2650fps. The Core-Lokt is a very good projectile but at this velocity is best utilized for close range hunting.

WinchesterOlin have stepped up the performance of the Roberts through the 117 grain Super-X Power-Point at 2780fps. This load is designated +P, denoting that ammunition is loaded higher than SAAMI (Sporting Arms and Ammunition makers Institute) pressure specifications, roughly 5-7% . Initially, the +P load was promoted as quite a big deal but today, it is recognized as a fairly standard load for the Roberts. Winchester Olin use a 24” test barrel to obtain these velocities while most sporting rifles, including the M70 XTR feature 22” barrels. Nevertheless, velocity loss is fairly small, as the Roberts cartridge is not loaded with huge charges of slow burning powder. On average, hunters can expect approximately 2750fps from the Olin loading.

The Power-Point is a fast expanding and potentially violent wounding projectile but at Roberts velocities and due to the rather dumpy shape of the Power-Point, these virtues can easily be lost at ranges beyond 100 yards. Again, the difference between wide and narrow wounding is entirely dependent on shot placement. The 117 grain Power-Point is not a particularly deep penetrating projectile but in the Roberts, produces a good balance of wounding versus penetration. The Power-Point is adequate for quartering away shots on game weighing up to 150kg (330lb) although a lot of wounding energy is lost on large animals if the bullet has to first traverse through gut fiber.

Federal list one load for the Roberts, the very useful 120 grain Nosler Partition. Muzzle velocity is listed at 2800fps for, on average, a 40fps loss in 22” barreled sporters. The front core of the Partition is, as mentioned throughout this knowledge base, incredibly soft and fast expanding. The rear core, especially at Roberts velocities, maintains its integrity, helps the projectile maintain velocity during penetration and in doing so, maximizes wounding throughout penetration. Again, shot placement is key.

Hornady list two loads for the .257 Roberts, the 117 grain Interlock BTSP at 2780fps and the 117 grain SST as a Superformance load at 2940fps. The standard BTSP at the more usual 2720fps performs much like the Winchester Power-Point. The Interlock is slightly more malleable making it less fragile than the Power-Point but in the Roberts, the differences on game are unnoticeable.

Although the Superformance load at 2940fps may seem to some an impossible accomplishment, Hornady manage to achieve this goal. Prior to 2010, Hornady utilized long drop tubes to pack a large dose of H4831sc into the Roberts case. Now, using a slow burning but high bulk density powder, the same results can be obtained with normal charges. In 22” barrels, velocity is usually some 70fps to 100fps lower than 24” barrels for an average 2855fps. The SST is the most violent wounding of the heavy .257” projectiles however penetration is similar to both the Power-Point and Interlock BTSP.

The 117 grain SST is an extremely good load with little peer. More about the SST can be found in the hand loading notes ahead.


Hand loading

Hand loading can certainly help increase the performance of the .257 Roberts. Like other cartridges in the 57mm family, the Roberts needs a 24" (600mm) barrel to obtain maximum velocities. Unfortunately, most Roberts rifles apart from custom builds, feature 22” barrels.

The most responsive powders for the Roberts are the medium slow burners in the 4350 range. Slower burning 4831 variants can be used to push 117-120 grain bullets at maximum velocities in 24” barrels but loads tend to be sluggish with anything less than near compressed charges.

In 22” barreled sporting rifles, 85-87 grain bullets achieve 3150fps, 100 grain bullets can be comfortably driven at 3000fps and 117 to 120 grain loads driven at 2800fps. In 24” barreled rifles and with careful load development, velocities of 3250, 3100fps and 2900fps can be achieved without excessive pressure. Obviously, if maximum velocity is the goal, long action rifles can reamed to .25-06.

Sierra produce a 75 gr flat based hollow point, an 87grain flat based soft point as well as the 90 grain hollow point GameKing. These bullets are all designed for varminting but can be used on light bodied medium game. For best performance, as with other brands, the light weight Sierra bullets should not be used on game weighing above 40kg (90lb). It also pays to remember that although the lightweight .257” bullets can be driven fast, BC’s tend to be below .300, suffering immediate and rapid loss of velocity.
Medium game bullets from Sierra include the 100 grain GameKing BTSP, the 100 grain Pro-Hunter FBSP, the 117 grain GameKing BTSP, the 117 grain Pro-Hunter and lastly, the 117 grain GameKing HPBT. Sierra also produce a 100 MatchKing with a BC of .394.

The 100 grain bullet weight has its advantages in the .257 Roberts. Although the 100 grain Sierra GameKing driven at 3000fps may seem somewhat light and frangible for use on medium game, in truth, .257” 100 grain projectiles lose velocity very quickly. The 100 grain Sierra GameKing has a BC of .355, this is an extremely good lighter medium game bullet but it does lose its ability to create hydrostatic shock and explosive wide wounding beyond 150 yards (2600fps). Launched at 3100fps, this range is extended to 180 yards. In its favor however, due to its light weight and low SD, full expansion is assured at velocities of 2200fps and lower (between 300 and 400 yards). The 100 grain GK does its best work on game weighing up to 60kg (130lb) while thin skinned game weighing 80kg (180lb) should be considered the sensible upper limit.

The 100 grain GK can be used in conjunction with the stout 100 grain Pro-Hunter. BC of the Pro-Hunter is .330 which for all intents and purposes equates to an identical trajectory out to and beyond 300 yards. The 100 grain Pro-Hunter is quite capable of tackling game weighing up to 80kg but it should always be remembered that a small caliber/ light bullet has its limitations as far as wound potential goes. The 100 grain Pro-Hunter is best utilized in bush/woods hunting situations, ideal for quartering shots on game at point blank ranges or across gully faces, out to ranges of around 150 yards, after which, the GK comes into its own.

The 117 grain GameKing and Pro-Hunter can also be used as a dual loading. BC’s are .410 and .388 respectively. As stated in the performance section, there is certainly a reduction in wounding potential when using these heavier bullets due to the slower muzzle velocities of 2800fps. Nevertheless, it is imperitive that bullet weights be matched to game weights as much as is possible. Compared to the 100 grain bullets, the 117 grain Sierra bullets are capable of deeper wounding on thin skinned game weighing between 80 and 150kg (130 to 330lb. On tough animals such as wild Boar, at body weights of 80kg (130lb), none of the 100-117 grain soft point .257” bullets are ‘ideal’, regardless of brand. Hopefully this comment helps paint a larger picture of what the hunter should expect. A respect of limitations and care towards shot placement are keys to success when using the Roberts on tough animals.

Hornady varmint bullets include a 75 grain HP, the 75 grain V-Max, and an 87 grain soft point. Again, these are better suited to varmints but are adequate on game weighing up to 40kg.

Medium game bullets from Hornady include the 100 grain Interlock SP, the 110 grain InterBond, the 117 grain BTSP Interlock, the 117 grain SST, the 117 grain round nose and finally, the 120 grain HP.
The 100 grain Interlock is mild performer, it is softer than the likes of the Pro-Hunter, is adequate for lighter medium game but certainly not a bullet that draws attention. The same can be said for the 120 grain HP, another very soft bullet. The 117 grain Interlock (BC .391) is a nice bullet, a good inexpensive option for hunters on a limited budget. This is a soft, fast expanding bullet, adequate for thin skinned game weighing up to 120kg at a push. The round nose bullet is not really very useful in the Roberts, even though it was designed for this cartridge. The increased frontal area does not really show any improvement in terminal performance in comparison to pointed soft point designs. Instead, the round nose tends to limit retained velocity (BC .243) out at 100 yards which is counterproductive to wounding.

The 110 grain InterBond is an excellent design. This bullet very much helps optimize/ find the balance between wounding and penetration on game weighing between 80kg and 150kg at close to moderate ranges. The InterBond is primarily designed for the .25-06 but is quite suitable for the Roberts within certain applications, giving best performance inside 150 yards.

The 117 grain Hornady SST is quite unique. Hornady used a flat based bullet design to minimize jacket core separation and they got it right. This particular SST produces very controlled, uniform wounding combined with relatively deep penetration, usually producing a .5 to .75” exit wound with chest shots. Internal wounding of soft vital tissue is violent yet inspection of muscle and bone, both on and offside, shows uniformity and repeatability. The SST works well on light bodied animals through to larger bodied medium game weighing up to 150kg out to ranges of around 300 yards. The 117 grain SST has a BC of .390. As external ballistics go, this is a relatively low BC. Nevertheless, the desirable field performance of the SST demands an attitude of compromise in this instance.

Speer bullets include the 87 grain TNT HP, an 87 grain soft point, the 100 grain Hotcor, the 100 grain BTSP, a 100 grain HP, the 120 grain Hotcor and a 120 grain BTSP.

The 100 grain Hotcor and BTSP can be used as a dual loading in the same manner suggested for the Sierra bullets. The major difference is that the Speer BTSP is extremely soft and although Sierra’s GameKing is frangible at close ranges, this bullet is more so, disintegrating into the smallest of fragments. The Speer 100 grain BTSP is best suited to game weighing less than 60kg (130lb) at all ranges. BC is .393, typical of Speer’s ability to produce sleek bullets. The 100 grain Hotcor is an excellent bullet, it produces immediate energy transfer and relatively deep wounding. That said, due to the caliber and achievable velocities, performance is limited. The 100 grain Hotcor is able to tackle game weighing up to 80kg but whether or not it can do this immediately and emphatically is another thing.

The 120 grain Speer Hotcor should be given a medal for long service. It has been with us for many decades and is a benchmark bullet in the .257” caliber. This bullet has been a traditional choice for hunters tackling game in the 80 to 150Kg (130-330lb) weight range for its ability to produce adequately broad wounding combined with acceptable penetration. On cross body shots on larger bodied deer, the 120 grain Hotcor will often produce a free bleeding exit wound.

The 120 grain Speer BTSP is again, exceptionally soft. This bullet is well suited to open country hunting, maximizing wounding at ranges beyond 200 yards- readers must remember that in the Roberts, velocity is already down to 2400fps at 200 yards if using 120 grain.257” bullets at a muzzle velocity of 2800fps. Dual loading the Roberts should not be overlooked due to the extremely high BC of the 120 grain BTSP at .480. This is something the excellent Hornady SST cannot achieve and for those wanting to push the range limits of the Roberts; an extremely soft, highly frangible 120 grain bullet is the surest means of maximizing wounding on game, regardless of bodyweights, at impact velocities of 2000fps (460 yards). The Speer 120 grain BTSP stands alone in this regard, slightly stouter than the Berger VLD but softer than other brands.

Nosler bullets include the 85 grain Ballistic Tip, the 100 grain Ballistic Tip, the 100 grain Partition, the 110 grain AccuBond, the 115 grain Partition, 115 grain Ballistic Tip and the 120 grain Partition. The Nosler Ballistic Tip bullets are identical in terminal performance to Sierra’s 100 and 117 grain GameKing bullets.
At Roberts velocities, The 100 grain Nosler Partition arguably the most useful, most versatile bullet available of the .257” offerings. The Partition can be driven at 3000fps or above to optimize wounding without suffering any risk of bullet blow up on medium game. The 100 grain Partition produces violent wounding, its only weakness being a mild BC of .377 which simply cannot be helped. Statistically, this is one of the most common projectiles used in the Roberts on deer in the U.S.

The 110 grain AccuBond is, like Hornady’s InterBond, designed to be launched at .25-06 velocities. The AccuBond is a good performer out to moderate ranges when used in the Roberts however, performance is less violent and less emphatic than the 100, 115 and 120 grain Partition bullets. The Partition is simply excellent for medium game hunting, the kind of item that reloader’s should always have a stock of, regardless of whether it is to be used as the normal load or put aside for special hunts. Nosler’s heaviest bullet, the 120 grain Partition has a BC of .391. This bullet is adequately suitable for game weighing up to 150kg, showing somewhat wider wounding combined with deeper wounding and penetration than competing designs.

Swift produce two stout bullets, the 100 grain A-Frame and 120 A-Frame. Both have acceptable BC’s of .318 and .382, similar to other brands. The A-Frames are tough, not quite as violent as the Partition bullets but very uniform regarding both wounding and penetration.

Barnes produce the stoutest .257” bullets. These include a 75 grain X, an 85 grain X, a 90 grain XBT, the 100 grain XLC (coated), the 100 grain TSX and 115 grain TSX. The light 85 and 90 grain bullets are well suited to hunting game weighing between 60 and 100kg (130-220lb) but do their best work at impact velocities of above 2600fps. The 100 grain Barnes bullets are not ideally suited to light bodied game. These bullets need quite a bit of resistance to initiate fast killing. If used on light bodied game, it is imperative that major bones be struck in order to effect fast killing. This does not mean that the Barnes will not expand if it strikes only light resistance. The Barnes 100 grain bullets do fully expand with light resistance; slow kills are more relative to the fact that the Barnes does not impart energy by shedding bullet weight, combined with limitations of the cartridge and caliber versus light game weights. Ultimately, the Barnes bullets should be selected with care and used appropriately.

If the hunter is determined to hunt large bodied medium game using the Roberts, the 100 grain TSX or XLC are both capable of producing violent wound channels and deep penetration at close to moderate ranges. The 100 grain Barnes bullets excel in this role. The 115 grain TSX is not fully necessary in the Roberts unless the hunter is truly under gunned. Low muzzle velocities tend to limit wounding potential therefore the heavy TSX should only be used for the toughest situations..


Closing comments

Both the .257 Roberts and the wildcat .25-08 have a small but staunch fan base. These cartridges often fill a specific niche rather than serve as general purpose medium game cartridges. The .25 caliber is often prolific in areas where the majority of medium game weigh between 20 and 60kg (50-130lb) and in such situations, the Roberts shines. As game weights increase, the hunter must be more vigilant as to the strengths versus limitations of the Roberts.


Suggested loads: .257 Roberts Barrel length: 22”
No ID Sectional density Ballistic coefficient Observed MV Fps ME
Ft-lb’s
1 FL Win 117gr Power-Point .253 .240 2750 1979
2 FL Federal 120gr Partition .260 .391 2760 2029
3 FL Hornady 117gr SST LM .253 .390 2855 2117
4 HL 100gr Sierra GK .216 .355 3000 1998
5 HL 100gr Sierra GK .216 .355 3100 2134
6 HL 120gr Partition .260 .391 2800 2089
7 HL 120gr Partition .260 .391 2900 2241
RR

 

[nvbroncrider]

Dang good article thanks