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.257 Roberts


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, 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 Whelen 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 chosen cartridge over all length (COAL) was also very short. These combined factors resulted in a very under powered cartridge producing velocities in the order of 2650fps which shed velocity quickly due to the round nose bullet design. In this configuration, the Roberts offered nothing over the .250-3000.

At the time of its release, there was no such thing as a short action rifle. But in those times, it was common for hand loaders to stick to factory designated COAL's. However, those who were more keen, soon learned that the Roberts could be loaded long and fast. 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. This was further compounded when the Roberts was later housed in short action rifles, whether factory or custom. Finally, 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.



It is immensely important to understand that the smaller, the bore, the more it is reliant on high velocity in order to produce wide wounding and fast killing. Having said this, if the bullet is to be driven fast, it must also be capable of maintaining some weight if it is to produce adequate penetration.
It has been said that the Roberts can do quite fine when housed in short actions however such information can be misleading. For example, if using modern plastic tipped 110-120 grain bullets in a short action Roberts, these are forced to be seated so deep, that the ogive is inside the case mouth. And while one could suggest that the simplest way around this is to use a more traditional soft point bullet design, a plastic tipped bullet like the Hornady 117gr SST driven as fast as this cartridge will allow can help enhance killing as a result of its overall bullet design - for the sake of the animal. It is also possible to increase velocities with modern powders in some rifles, enabling the 117gr SST and like weight kin to be driven up to and above 2900fps. In this instance and again with regards to small bore performance, an extra 100fps can make a difference in speed of killing when hunting out to 300 yards. Having said this, we should never sacrifice accuracy for velocity, the two must go hand in hand. It is worth noting that Hornady factory SST ammunition does break the 2900fps barrier- but does so by utilizing a longer than traditional COAL of around 73.5mm or 2.893", again suited to medium or long actions.

With regards to velocity, a 100 grain bullet (e.g. the excellent  Sierra GameKing) driven from the Roberts at 3000 to 3100fps produces fast kills on light framed medium game and can be very useful for hunting out to ordinary hunting ranges (300 yards). Nevertheless, a bullet such as the Hornady SST can have a tendency to produce more uniform and emphatic results across the impact velocity spectrum with regards to both wounding and penetration versus game of varying body weights.
Once initial velocity is shed (whether we reach 2800fps or 2900fps), shot placement is the key factor. The hunter must always try to break foreleg bones of medium game in order to maximize bullet expansion, wound trauma and also, destroy the autonomic 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. If hunting larger bodied deer with a Roberts, this may require the use of a bullet like the Nosler Partition.
The forwards shot at close to moderate ranges is not difficult, though it can require a certain measure of discipline to implement if this shot placement is foreign to the shooter. The greater difficulty is maintaining the discipline to not aim behind the shoulder at extended 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 autonomic plexus and forward lungs are keys to consistent performance in the Roberts. By the same token, the Roberts is not an ideal long range deer cartridge due to potential narrow wounding at lower velocities in the absence of ideal shot placement.
The .257 Roberts is a low recoiling, mild powered cartridge. In a short action, it has the potential for a suitable youth rifle but without care towards optimizing hand loads, can lack 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 medium or long action rifle and is best suited to adults or teenagers who, for whatever reason, are unable to tolerate recoil. All romantic notions and nostalgia should be put aside when using this cartridge for the sake of the animals hunted. Attention needs to be focused directly towards optimal killing.

The Roberts is very similar to the 6.5x55 or .260 Remington when the latter are loaded with 120 grain bullets. The bullet diameters are literally a 'cat's whiskers' apart and bullets of the same brand and type produce identical performance in the field.

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Factory Ammunition

With modern powders, factory ammunition makers are now able to produce high 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.
Winchester Olin 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 lightweight quartering away shots on lighter weight animals, but on game weighing around 150kg (330lb), a lot of wounding energy is lost if the bullet has to first traverse through gut fiber. With such shots, animals will typically run long distances before expiring and without an exit wounding, tracking can be difficult.
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. It is important to note that the Nosler projectile used in this factory load is not the same as the 120 grain Partition bullet available to hand loaders. The factory loaded bullet is of an exclusive design, its ogive shortened slightly to allow it to be housed in short actions, the standard bullet being too long. 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. 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  In 24” barreled rifles and with careful load development, velocities of 3250fps, 3100fps and 2900fps and higher can be achieved without excessive pressure. Although the Roberts does its best work on game when loaded fast, there are obviously limits. Those who cannot stop themselves from pushing the limits, may need to consider reaming their Roberts rifle to .25-06 if utilizing a long action.

The .257 Roberts is truly at home when housed in the medium length Mauser M98 action which was based around a 57mm case design. There are many examples of such custom rifles in the U.S that have been cherished and well cared for over the years. Besides this type of action, the .257 is best utilized in long action factory rifles.  The bullet selection information given below is in some instances based on rifles which allow for generous COAL's. Those who own short magazine rifles need to take this into consideration. The sleeker and heavier the bullet, the more likely the riskof COAL problems.

Sierra produce a 75gr 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 imperative 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 (88lb).

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 repeat-ability. 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 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 body weights, at impact velocities of 2000fps (460 yards). The Speer 120 grain BTSP stands alone in this regard and although match style bullets do offer higher BC's, these do not feature the wide frontal area of the Speer for rapid expansion.
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 is 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 but not quite as violent as the Partition, however these do boast excellent wounding and penetration. These bullets do their best work at higher impact velocities so for best results, it pays to keep ranges reasonable and aim to break bone.

Barnes produce the stoutest .257” bullets. The main include a 100 grain TSX, a 115 grain TSX, an 80 grain Tipped TSX and a 100 grain Tipped TSX.

Previous bullets have included the 75 grain X, an 85 grain X, a 90 grain XBT, the 100 grain XLC (coated).

Barnes bullets do their best work at impact velocities of above 2600fps with regards to hydrostatic shock for fast killing and above 2400fps with regards to wide wounding, a general rule throughout the small bores.

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 versus light game weights. Ultimately, the Barnes bullets should be selected with care and used appropriately.

The 80 grain TTSX (and TTSX in general) attempts to remedy these problems. The reduction in weight enables the hunter to increase velocities while the bullet meets more resistance on impact for increased energy transfer. These factors combined with a wide hollow point help a great deal to initiate wounding. And while the homogenous bullet designs do struggle at lower impact velocities, this bullet does work well out to ordinary hunting ranges and can be pushed to 2200fps, though best performance does occur at impact velocities above 2400fps. As for game weights, this bullet can be put to adequate use on most deer species.

If the hunter is determined to hunt large bodied medium game using the Roberts, the 100 grain TSX or better still the TTSX are both capable of producing violent wound channels and deep penetration. Again, ranges versus potential impact velocities need be taken into consideration, the higher the impact velocity the better.  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

The .257 Roberts certainly has a great deal of history behind it, yet is a story filled with contradictions whether discussing history or usage. One account suggests that 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. It is no great leap to think that Roberts was attempting to improve upon the .250-3000. However another account suggests that Ned Roberts wanted a mild cartridge so as not to disturb his neighbors. Perhaps we will never know the exact details surrounding this.

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 with high velocity loads. As game weights increase, the hunter must be more vigilant as to the strengths versus limitations of the Roberts. In some situations, buying a rifle due to its light recoil simply does not cut it if we are to put animal welfare first. Sure, a light recoiling mild powered cartridge can be useful, but then you have to know how to use it.

One of the downsides of modern gun literature is that at times, writers become too invested in Nostalgia. The Roberts is often romanticized beyond reason which can have a negative downstream effect. While one hunter writes tales of joy with fast stepping hand loads, another experienced hunter looks back on 40 years of hunting with mild factory loads and curses the family rifle that was passed down to him. Within my own mail, I have seen both sides of the coin, readers who love the Roberts versus readers who loathe it. Those who love it tend to know how to extract maximum velocity and accuracy potential from their rifles while also selecting bullets well suited to the job at hand. Such a set up seldom gives any trouble, a 115-120 grain bullet driven at over 2900fps is no slouch. On the other side of the coin, with slow loads, a poor choice of bullet and with less than ideal shots (including bush / woods / swamp snap shots), it is easy to get ourselves into a whole bunch of trouble. One should be able to see from these basic examples, how both the man who loves the Roberts and the man who loathes it, both speak the truth based on their individual experiences. 

Suggested loads: .257 Roberts Barrel length: 22”
No ID   Sectional Density Ballistic Coefficient Observed  MV Fps ME
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
Suggested sight settings and bullet paths           
1 Yards 100 150 225 260 300 325    
  Bt. path +3 +3.3 0 -3 -8 -12    
2 Yards 100 150 240 280 300 325 350  
  Bt. path +3 +3.3 0 -3 -5.2 -8.2 -11.6  
3 Yards 100 150 252 290 325 350 375  
  Bt. path +3 +3.5 0 -3 -6.6 -9.7 -13.3  
4 Yards 100 150 263 305 325 350 375  
  Bt. path +3 +3.6 0 -3 5.3 8.2 11.6  
5 Yards 100 150 275 315 350 375 400  
  Bt. path +3 +3.7 0 -3 -6.6 -9.7 -13.2  
6 Yards 100 150 245 285 300 325 350  
  Bt. path +3 +3.4 0 -3 -4.6 -7.5 -10.8  
7 Yards 100 150 257 295 325 350 375  
  Bt. path +3 +3.5 0 -3 -5.9 -8.9 -12.4  
No At yards 10mphXwind Velocity Ft-lb’s
1 300 13.9 1794 836
2 300 7.8 2139 1219
3 300 7.5 2219 1279
4 300 8.1 2253 1126
5 300 7.6 2343 1218
6 300 7.7 2173 1258
7 300 7.3 2259 1360
Note: Loads 5 and 7 for rifles shooting faster than normal loads, custom rifles etc.
257 roberts final.jpg

  Imperial Metric 
A .473 12.01
B .472 11.99
C 20deg 45’  
D .430 43.89
E .290 7.36
F 1.728 43.89
G .221 8.16
H 2.233 56.72
Max Case 2.233 56.72
Trim length 2.223 56 46

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