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

2900-2940 22" bbl

Speer data would indicate you're leaving a few hundred fps on the table with that one.

Did you clock it?

DF

I use IMR-4831 for my Swede.

That's not to shabby.

Burn rates pretty close, all those in the same neighborhood..

DF

Agree with Dirtfarmer. With heavy bullets I used to use RL22, have replaced it with RL23. Norma MRP is very good.

RL26 has worked good also, heavier bullet the better. My model 70 did 3129 FPS with RL26.and 115gr Partitions.

RL23 did 3129 FPS with 115gr Nosler Partitions

RL17 also did over 3100 FPS with 110gr Accubonds. Had to back load off.

Did you get unburned powder residue with '26 in your Roberts?

I was using heavy bullets and got granules in the chamber such that I couldn't chamber the next round. Once I shook it out, all was good.

Swore off '26 in the Roberts. It's the cat's meow in the 7RM with 160's. I have a big jug and really like it. Just not in the Roberts.

I have Pw Pro 4000 and StaBALL, just haven't tried either in the Roberts. Too many projects, not enough time....

DF

After looking high and low for RL22 or MRP locally, I think I’m going to try IMR4831, Ramshot Hunter, and RL17. Hopefully, one of those will give acceptable results. If none of those work out I guess I’ll order some RL22 and/or MRP.

Those are all good candicates.

When you go to get more RL-22, get RL-23 instead. Better powder that will do about the same thing.

DF

I’ll keep that in mind.

H4831sc with 115/120gn bullets in my Roberts'.

Thanks

Do not remember any granules left over after firing. I usually use 215M primers or CCI250 primers

I shoot the RL23 and the MRP the most as I think they are a little more accurate. Like I said I had good luck with RL17

But do no use it much in that Caliber. I use it in my 7mm-08 mostly

I see you are using PP4000MR. Are you having any luck? I,m trying to make a load for my 7mm-08

So far limiter success, but last load using WLRM primers and 145gr Speer BT bullets I got 2895 FPS but SD was 28.4 not good.

For any 120, my go-to is 43 grains of H414 and Fed 215 or 215M primers. .257 seem picky, inconsistent, but that has worked in several rifles for me.

Tom

No one said it so maybe I am old and out of date... I use IMR 4350 in my rem 722

I was thinking about that as well. I saw that one in my Ken Waters book.

Nothing wrong with being a vintage type guy, using vintage stuff.

It worked back in the day; it works now.

Sorta vintage myself.



DF

I used to shoot IMR4831 with the 120 Partition in a 22" short action 700 Roberts. It made around 2,800fps. Killed deer nicely.

Good news! The gun shop called this morning and set back 1 lb each of RL23, and PP4000. So, it looks like I have a bunch of powders to try now. As soon a Grafs ships my MRP, I’ll have enough variables to keep me crazy for a while.

MRP is about the same burn range as RL-22. Some say it’s a better refined version.

My Swede sure likes it with 139 Scenars.

DF

I'll have to try that. I guess my loonyism is now confirmed.

Yep, without a doubt.

DF

Like I needed confirmation. I once bought a savage 99 in 250-3000 just to shoot up two old boxes of ammo that someone gave me.

Ha!

You there, don’t need any confirmation.

DF

I used AA 3100 which is about IMR 4831, burn rate in my 257 Roberts with 120 gr Speer or NP several years back.Also used RL 19 & IMR 4350 in my 257 AI with 120 gr bullets.

I wonder why the low velocity with 7828??? Most pf the data I've seen for other cartridge show it close to RL-22. In fact, when I was looking for RL-22 for my .280, none was on the shelf at the LGS. Checking in a couple of manuals showed velocity to be very close to RL-22 so I used that. My .280 didn't like it. I got the speed but no accuracy. Strange that Speer has it so low over the velocity lever. I wonder why????
Paul B.

That is a good question. I've noticed that my Speer manual(#14) is pretty conservative on velocities for most of the rounds that I load.

Ramshot Hunter has worked really nicely for me in the Roberts from 90s-115s.

That is one that I'm going to try. Along with RL-23, IMR4831, and PP-4000MR. I really like Ramshot powders and have been using more and more of them lately.

I used IMR4350 with 115gr partitions or any 117gr bullets load was 43.5gr in my 760 Remington pump. Velocity was about 2925 FPS.

I could live with that.

The best powder I have found is RL23 which is a improved version of RL22, it is temperature insensitive and provides the same speed.