Home Forums Reloading Big Game Rifles 257 Weatherby Mag - BEST LOADS !

I'll add to the redundancy - 70gr R22 / 100TSX.

Lyman 48 lists a load of 73.0 grains of H-4831 under a 75-grain Sierra giving 4048 fps.
Sierra listed 70.5 grains of IMR4350 under their 75-grain HP giving 4000 fps. I assume their bullet is good for that velocity since they provide data up to 4000 fps. Of course the true Sierra max load is somewhere above this - but we don’t know if it’s 4001 fps or 4099 fps.

Both used 26” barrels, the former load would likely be close in a 24” barrel. That said, there is nothing a 75-grain hollowpoint will do at 4000 fps that it won’t do at 3900 fps. It’s just a number, albeit a cool one.


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my 257 Weatherby Mag. rifles like Reloader 22, you are going to like this old speed cartridge.

My current Accumark shoots very well with 69.0 grains of IMR7828 under the old Hornady 120 HP, a bullet specifically designed for big case .25s. Velocity is 3342 fps and the last four groups I fired (not cherry picked) averaged 0.67. Sadly this bullet is out of production, but it does almost as well with 120 Speers..

72 gr. re22
100 gr. TSX or TTSX
CCI 250 primers
3700 FPS

Work up in your gun as always. This is a stiff load.

RE-22 under 110 AB's.

IMR-4831 under a 100 TTSX.

Both worked great in my Backcountry.

Pick your flavor and slay critters.

I've was given a Weatherby Vanguard in .257 Weatherby Magnum by a very good old mentor and friend recently. Looking for loads online, I stumbled upon this old thread. Loaded up two three shot groups worth of ammunition and hit the range. First load I loaded pretty conservatively. The second load....Hanco, I went off of this I think I'll be going with the 67gr. of RE-22, 115gr. Nosler Ballistic Silvertips, 3223 fps.

That’ll work!

THIS

If the temperatures you hunt in don't vary from the 20s to maybe 80, then RL-22 works fine. Which is true of most of today's smokeless rifle powders.

But have found more temperature-resistant powders perform more consistently beyond those parameters, especially H1000 and Ramshot Magnum.

Working with 100 gn Nosler E-Tip (FN Mauser with a 26" Pac-Nor barrel):
H1000 gave the best results closely followed by Magnum, N560 and Reloder 26. All gave high velocity and tight groups.
LRT was good but gave slightly lower velocity than Magnum.
69 gn of StaBall HD made amazingly small groups at 3275 fps and deserves more development.

I offered information in this thread several years ago in 2016, page 2.

Since then I acquired a new 22" tikka takeoff barrel in 25-06 for $75. I just had to use my 257 Roy reamer when I discovered it was the same thread size as a post 64 model 70 in my collection. Shortened the shank a bit and opened up the chamber.

Previous Roys I posted about were all 3 groove Liljas. The Tikka is a 6 groove so I now know the reamer's custom specifications works accurately with at least one other groove configuration.

Results: Model 70 257 Weatherby, 22” new tikka barrel Berger 115 VLD
68 gr of SCC IMR 7828 fed 215 match velocity 3280 ave
60 degrees

Thinking of trying RL-33 for grins to see how it compares to the longer 27 1/2" barrel.

after looking thru the Berger reloading book about the 257 Weatherby mag. i trIed Reloader 25 and my groups were even better with this powder over Reloader 22 ,i have also started using Hammer Hunter 103 gr. bullets that do group better with than Barne`s bullets for me in my 10 twist Brux barrels and my 8 Twist Brux barrel . I have only killed 3 big game animals last fall with this combo but plan on using Reloader 25 and 103 gr. Hammer Hunter bullets again this fall 2023. good luck with you combo choice,Pete53

https://imgur.com/a/NpifKLD


Accurate

I'll leave the grains to you, but RL 22 or IMR 7828 are the go-to powders.

I had some marginal results with the 100ttsx and tried the 92 grain Hammer hunter.Probably could have gotten more out of it but stopped at close to 3850 and so far good results on game out to 450