There has been lots of discussion lately about the .257 so I thought I would start one concerned with only the 115-120 gr. bullets. I know most use the 100 gr bullets and I do too. But I do like the way the 115 gr Partitions work on big hogs not the little “grillers” as I call them. My best load for accuracy has been with RL 22 but Ramshot Magnum worked well too. What powders especially the slower ones have you guys had the best success with in the 115-120 Gr. bullets.

I have several, and in general, have had better luck with H4331sc for 120's. For me, a good 120gr at 2900ish is a sweet spot considering terminal performance, trajectory, recoil, and accuracy.

Magnum for me as well with 120 NP.

H4831 for me with the 115NBT and 120 NPT

115 gr NP
H4831 in two Ruger 77s, one is a LT.

H4350 in another 77. All 22" barrels

H4350 with one of mine with 117’s, 42.5 gr gets me 2750 for a mild, yet very accurate load. With the 115 partition, 120 Speer, and 110 accubond, IMR 4831 has been very accurate, with good velocity in +P loads.

Old70

I am using 115 gr. Nosler Partitions and 43.5 grs. IMR 4351. About 2900 fps. from my Kimber Montana and get one inch five shot groups. All round load for everything up to 300 yard elk.

Boring...

RL26,RL23, Norma MRP, IMR7828SSC, RL17.
The first three are my favorite. RL26 gives the highest velocities
with the least pressure.

H4831 & 115 NBTs...

My 257 really likes Ramshot Hunter under a 115 NPT. Perks them at 2950.

43.5 grains RL 19 w 115 ballistic tips
43 grains RL 19 w 117 btsp interlocks

These should only be running 2800's but have no problems with deer out to 370 yrds, and both loads are very accurate in my m77.

I have used both IMR 4831 and Big Game with 120 NP.

I got better accuracy with the IMR 4831, but only by a tiny bit.

I now use Big Game all the time, because it meters through my powder measure so much better. It just makes reloading easier.

RL22, RL25, Retumbo, H4831 have all worked well for me with bullets ranging from 110grs to 120grs. RL22 has been my go to powder for years with the 117gr-120gr bullets. This combination has been accurate and consistent with good velocity.

I am another one who found IMR4831 to be good with 120 grain bullets. This goes back into the 1980's, I don't have more recent experience.

Jim

Same here.

Haven't tried them in the Roberts but impressed with what they do in .243, 6mm AI, 25-06, 6.5x55, 270 win. especially R26.

I had very good luck with superformance and Hornady 117 RN in my Montana.

Funny, puzzling thing. I'm on my 5th, I think, .257 Roberts. I'd expect the heavier the bullet, the slower the powder. I've had the best luck the most often with 100s and H4831, and I got my best accuracy with the 110s with RL22, but instead of something slower yet, I've gotten the best accuracy out of 120 grain bullets with 43 grains of H414 and magnum primers.

No point in fighting with what wants to work.

Tom

Superformance works in my 257 Roberts and my 270 win with 140gr bullets.