Home Forums Reloading Big Game Rifles Your most accurate .257 Roberts load with 100 gr. Partitions?

I'm not having any luck finding an accurate load for my .257 Roberts with 100 gr. Partitions, can anyone suggest a load that produces good accuracy?

38 grains of Varget was recommended to me, but I haven't tried it yet. Still playing with H4350 for 110gn ELD X and H4831 for 117gn SST.

Gunswizard, what powders are you using?

I gave up on the 100 Partition in my Kimber; just wouldn't shoot with decent accuracy. The Sierra 100 ProHunter and 100 Barnes TSX BT were far better, both with H4350.

I have tried IMR 4064, IMR 4350, H4350, RL-15, H100V, Varget. I am using WW +P brass and CCI 200 primers seating to loading manual/manufacturer specifications. 100 yd. 3 shot groups have been running 1 1/2"-1 3/4", not the tight cloverleaf groups my rifle shoots with Sierra Game Kings and Nosler Ballistic Tips. I am beginning to think that my rifle just doesn't like Partitions.

Have you played with seating depth?????

I am about to try some 115 NPs in my R77 RL in the Bob.
It shot 100 BTs ok, but looking for a little stronger bullet. I shot an 8 pt buck and found the cup under
the off side hide. Had 48.2 gr of copper left. Yes, it killed the deer well enough, but.....

My Roberts didn't like NPT's as much as 110 NBT's and 100 TTSX, the former with H-4350, the latter with H-100V. Fast load with H100V with accuracy. And it's a "tougher bullet" that's a real killer.

LA 700 with 24" Brux. COAL longer than std.

DF

I haven't tried the Partitions in my M70 Featherweight, but they shot exceptionally well in the Browning A-bolt I used to have. My current load is the 90 gr. Barnes X bullet/45.0 gr. IMR 4350/CCI 200/Remington brass. It shoots .5 MOA all day.

Some guns seem to like Partitions more than other guns.

My .240 HS Precision SPL prefers the 100 gr. NPT over all others, like half MOA at 400 yds.

You just never know until you try them.

DF

My model 70 257 Roberts like 115gr Partitions the best. The powder it likes is Norma MRP. assume
that holds true for 100gr Partitions.

Probably a lot of snake oil in why some guns love the NPT, others not so much.

Can't explain it, but sure can test and observe the results; let the gun decide.

DF

To no one in particular: If a given bullet isn't shooting well for you have you checked if your dies seat them as straight as bullets that do shoot well?

Mine get checked with a Sinclair gauge, straightened with a TruAngle tool.

DF

I used WW +P brass, today I'd start with Nosler +P. Federal 210M primers. 48.0 grains of H4831SC.

My most recent 700 landed on that load for both the 100 grain partition and the 100 grain ballistic tip. The gun was basically a 700 LVSF with an aftermarket barrel. Leupold 4.5-14X and a Jewell trigger. The partition was pretty darn good, solidly sub MOA though I'd have to check my notes to tell you exactly how much, and the ballistic tips were just uncanny with that load, like 5 shot groups in the 0.2s.

I've had 5, I think, .257s. 3 of the 5 were never accurate with 100 grain bullets. For some reason, some of the guns shot well with light (75 grain especially) and heavy (120 grain) but not middle (100-110 grain) weight bullets.

I've had better accuracy more often with the 120 grain partition than the 100. If you try that, use a Fed 215 primer and 43 grains of H414. I've never had real good results from the 115 in any of my guns including those .257s, 4 .25-'06, and a .257 Weatherby. My go-to for hunting accuracy is the 120 grain partition.

I like .25s but they can be a bit finicky.

Tom

Yeah, they can sometimes be pretty finicky. But when you find that magic load, you got something. It's worth the effort.

With the heavies, don't forget H-4350. I recently found an 8# jug at Powder Valley, didn't take long to pull the trigger on that one. IMO, you can't have too much H-4350...

Nosler shows IMR-4350 as their accuracy load. H-4350 is a lot more temp stable than IMR-4350. I'll stick with the Hodgdon version. It's been very accurate and consistent with heavier bullets in my Roberts. H100V is, of course, the velocity champ in that round. But, it's not as temp stable as H-4350. Where I hunt, not a problem, but in some areas, a real consideration.

DF

Two observations here:

First, even if you check your handloads for bullet concentricity, the necks of some mass-produced cases are often considerably thicker on one side than the other these days. This will also affect accuracy.

Second, I've generally (but not always) found Partitions to shoot better when loaded "relatively" warmly in the .257 Roberts--which sometimes means powder charges above even +P loads. This is related to the advice given years ago by Gail Root, then the head bullet designer at Nosler, who suggested trying a faster-burning powder if Partitions didn't shoot as well as desired, to "bump up" the diameter of the rear of the bullet, thanks to the exposed rear core.

I've found the same principle often works with increasing the charges of the same powder, partly because even +P load data is only 58,000 PSI, notably less than other bolt-action rounds. I've found going a grain or two above .257 +P maximums often results in better accuracy with Partitions--though some rifles shoot them well with lighter loads.

To expand on MD's comment about stiffening up the loads, Hodgdon's 6mm Rem data for 100 grain bullets and "4350 class" powders tells us the Roberts isn't really cooking in a modern rifle until that 100 is coming out on the top side of 3100 fps.

Yeah, the old Roberts really comes alive at modern pressures. And new powders can enhance performance.

No reason the .257R can’t perc at 6 mm Rem pressures with good brass in a modern action. Those two are actually cousins.

DF

I'd be happy to use "4350 class" data for the 6mm and a chronograph to find the 257 load.

At equal pressure, the slightly larger .25 bore will shoot a 100 gr bullet slightly faster than a 100 gr bullet out of the .24 cal bore.

DF