Home Forums Reloading Big Game Rifles Good .257 Roberts loads

So in today’s world when we might be using powders & bullets that aren’t ideal, this thread came to mind. I searched the ‘fire for a bit but didn’t see a thread that offered current data inclusive of the new (pre-2020) options that ‘were’ available.

Thinking enough fresh info might be a nice cross reference as a person tries to build a load from sub-optimal supplies.

Anyhow, smoke ‘em if ya got ‘em - love to learn more about one of my favorite cartridges.

-pints

This combo works well on a LA gun, COAL too long for SA.

I have a Kimber 257 R that'd been a bit fussy until trying RE19 with the 100 TTSX. Had I not stumbled on that combo, it would be gone or wearing a new barrel.

I have a Kimber Classic .308 that now shoots a lot better with a 23" Broughton 5C SS barrel....

DF

My plain Jane BRNO Mauser works very well with RL 19 and the 90gr TSX's...but RL 19 supplies were spotty even before the Biden panic, so I am now using a stout published load of IMR 3031 for identical velocity and equal accuracy.

My Winchester Model 70 with 115gr Partitions, like Norma MRP, RL23, RL26, RL17, and RL22. All gave over 3100FPS, around 3130FPS. MRP and RL23 were the most accurate

If I pushed it I could almost get 3200FPS with the RL26. My model 70 has a fast barrel. The speeds were taken with 2 different Chronographs.

I got unburned powder with RL-26 and 115's in my 257R. So, I don't use it in that round.

Granules in the chamber kept me for chambering the next round.

I haven't tried StaBALL, but it's in the right burn rate. Hunter is pretty close as are RL-16 and17.

H-4350 and H-100V are the most used by me. 4451 should work, just haven't tried it.

DF

There is a thread on Ask The Gunwriters where a few of us are posting results with the .257 115 Partitions with the .525" ogive that are (were?) available at Shooter's Pro Shop for $18 a bag.
These are shooting sub-MOA in my M722 Roberts at over 3000 FPS with 51 grains of Ramshot Magnum. That's the only powder I have tried so far with this bullet. I got over 3100 with 52 grains but this just seemed a bit high to me, despite no pressure signs. I may have found a node at 50.8 grains and 3020 FPS. My next rip to the range I am trying a different primer to see if I can reduce ES (WLR instead of F215, which I've shot up to now), and trying .050" and .005" off the lands - previous work has been at .025" off. in my rifle, .025 off puts the case mouth right in the middle of the factory cannelure on that bullet, which was made for the Roberts by Nosler.

Cheers,
Rex

I'm still toying with the idea of a new barrel on this Classic Select but can't decide what chambering I'd want. If the mag box was longer than 2.8" I'd keep it a 257 R, so maybe a 250 Sav AI? If it didn't have such a nice stock, I'd send it down the road

I'm about out of RE19 and have some 3031 so will give that a try!

JGray, I got my load out of the old Sierra #3 manual. I suspect TSX's are a little more inclined to build pressure...all else being equal. So instead of using 87 gr data, I used 100 gr data for safety reasons. Sierra lists 38.2 gr of 3031 with a 100 gr spitzer flat base, getting 3,000fps for their accuracy load, in a 24" '98 Mauser. I ended up using 38.5 of 3031, 90 gr TSX for 2980 fps at 15 feet to the screens. Consistent sub moa 5 shots at 100 yds. I believe I have a SAAMI spec chamber, so I just seated the TSX's out to where the first band is exposed, never bothered to check distance to lands, but plenty of room in the magazine box too. Good luck.

Actually, the head guy at a major ballistic lab told me, years ago, that TSX's resulted in less pressure with the same powder charge than any bullet he'd ever tested--especially relatively light for caliber bullets, with fewer rings around bullet shank. The lowest-pressure lead core bullets tended to be Hornady Spire Points.

Boy...I'da lost money on that bet, who'da thunk it? I realize copper has a huge range of hardness, but I have pounded a lot of copper ground rods deep into hard rocky soils on rock crusher setups and they are not much softer than copper clad mild steel. Easily withstanding 40 or 50 blows from a 10 pound double jack.
Anyway, thanks, that is good to know...to be legal beagle here in the land of fruits and nuts, I've had to re-bullet my entire battery to accept copper bullets. I approached that over cautiously apparently. It does explain the very close chrono readings in the situations where I just pulled the cup and core bullets and re seated all copper.

It's been addressed here before, but I am still not clear on the pressure/velocity relationship. Intuitively, I'd like to think as pressure goes up...velocity goes up. Pressure goes down...velocity goes down. Given the same powder and bullet of course. But often , here and elsewhere, guys report pressure signs at velocities that in my mind, should not show undue pressures. Using an imaginary pressure/time graph...could an early high pressure peak, maybe shaped like a bell, result in a low velocity? Almost as if after the abrupt pressure peak the bullet actually decelerates a little before it exits the muzzle, am I on the wrong track here?

Two curves may certainly be such that one has a higher peak than the other, yet has less area under it.

Got a bunch-o recipes but the only one I use regularly in my custom LA is the 110 gr. NAB & H4350 sitting .050" off the rifling for a solid 3000 fps MV.

Curious no one reporting StaBALL loads. You'd think that one would perform well.

I have a couple of cans, just never tried it in the .257R.

Too many projects.

DF

flintlocke,

Yep, copper is pretty hard--but not as hard as the gilding metal used for most bullet jackets .However, because of this pure copper is also "grabbier" than gilding metal, which increases pressure.

However, the reason Barnes started producing the TSX was not so much pressure but copper fouling. There was plenty of contact between the longer bullet shank of Xs, so fouling built up rapidly--which also increased pressure as well. (Though the original Barnes Xs did result in more pressure than lead-cored jacketed bullets of the same weight and diameter.)

The grooved shank of the TSX reduced contact with the bore enormously--and hence fouling, as well as pressure.

Velocities are an indicator of pressure, but a lot depends on seating depth as well. Closer to the lands results in higher peak pressure.

The reason Hornady Spire Points usually result in less pressure than the same weight/bore diameter of other lead-core spitzers is partly because their shanks tend to be shorter, so have less bore contact. But Hornady also tends to use slightly harder lead alloys than many other bullet companies. This would intuitively seem to increase pressure, but it reduces the tendency of cup-and-core to "bump up" in diameter when powder gas boots them down the bore.

For an all-around powder, one of the 4350s is a good choice. If memory serves, Jack O'Connor liked 40 grains of 4064 under a 100 grain bullet in his Roberts. I like IMR 4831 for 115-120 grain bullets, as did Townsend Whelen. Hybrid 100-V gives the highest velocities in the Hodgdon manual.

Rifles chambered for the 257 Roberts can vary a great deal. I had a 1976 vintage Ruger 77 tang safety Roberts with a sloppy chamber and a very long throat. It would take 43 grains of RL-15 to get a 100 grain bullet to 3,000 fps. My current Roberts is a Savage Axis with an E.R. Shaw barrel and a short throat. The load I used in my Ruger would blow primers in the Axis rifle.

The Axis rifle with Shaw barrel will push a 117 grain Hornady boat tail to around 2,950 fps. That's 25-06 territory with less recoil. I owned and shot a 25-06 for many years. I prefer the Roberts.

JB,
There is a boatload of great information packed into that post - Thanks for that and all you share here.

Cheers,
Rex

Anybody wanting to get some of those Roberts 115 Partitions with the .525" ogive - there are less than 50 bags left on SPS. Unlike some of SPS' other blems, I wouldn't bet on these coming back, as it seems to have been a bit of a one-off run, but I could be wrong. I've been shooting 115 Partitions in the 25-06 for over 30 years and never ran into them before. But I have enough now to last forever. That kind of stubby ogive is just right for the short actions.

Cheers,
Rex