Home Forums Reloading Big Game Rifles Favorite Powder .257R and 120gr Speer GS

So, what is everyone's favorite powder for Speer Grand Slams in the .257 Roberts?

I don't shoot that bullet in my .257R., can't give you a fav.

I'd try H-4350. It does very well with the 115 NBT. H-100V worked well with the 100 TTSX.

StaBALL may be one to try. I got mine from Powder Valley, not sure if they still have it. Haven't shot it in the Roberts.

Some like H-4831 and RL-19. I tried RL-26. It left unburned granules in the chamber; I couldn't chamber the next round.

Maybe others will chime in.

DF

120 partitions here but H4831 was the ticket from mine.

I tried the Grand Slams in my Roberts with less than inspiring results.

I'll look at those. Everything is kinda thin on the ground here right now. I'll bet I can find some H-4831 though.

Would probably work great.

May be one to start with, stay with.

DF

I got them REALLY cheap. $2.50 per box at an estate sale. So I figured they would be fine for our little Texas whitetails. Hell, deer aren't that hard to kill.

I'm normally a 100 gr Ballistic Tip guy. I use a pretty mild load of 4320. It is loping along around 2,900. I rarely shoot over 125 yards when deer hunting on my lease.Little meat damage and they rarely run at all.

I figured if nothing else I could shoot up some hogs with them.

You can find a load, make them work.

Price was right.

DF

Speer data.

https://reloading-data.speer-ammo.c...25_caliber_257_dia/257_Roberts_P_120.pdf

They don't address accuracy, but do address speed.

DF


Edited to confess, ya gotta be a real hard core Loony to have every powder on that Speer chart...

I have more than I care to admit.

Card carrying Loony....

DF

That was part of the problem honestly. I just wanted to know where to start.

I tried some 7828 in mine and it loved it. It also shoots several other powders ok.

H4831 works great for 120s for me

What kind of velocities are you getting with the 7828?

I was thinking about trying IMR 4831 I don't have any of the H-4831. What kind of velocities are you getting with the H-4831?

In my 257AI, RL22 & H4831sc produced the best velocity with 120gn Speers.

Not a 257R but my 25.06 loves a full house of RL25 or RL22 with the Speer 120gr Hot -cors as well as the discontinued 120gr Deep Curls. In my experience both powders have always produced excellent results for me with bullets ranging from 110gr - 120grs in the .257 calibers.

I'll have to see if I still have any RL-22.

I’m using up my RL-22, replacing it with RL-23.

Have a big can of MRP, very similar burn rate. It’s my go to Swede powder.

DF