.257 Weatherby Magnum.
 

I just purchased a Remington 700 SPS Stainless chambered for .257 Weatherby Mag. I have never loaded for this cartridge, or any other Weatherby Mag. I am an experienced reloader, just not with the Wby Mags.

Is there anything "special" I need to know regarding this, or Weatherby cartridges in general? Does anyone have any pet loads they would like to share?

I intend to use it for hunting Pronghorns in WY and was considering the 100 gr. Nosler Ballistic Tip.

RE: .257 Weatherby Magnum.
 

There's several .257 Weatherby owners/shooters here and I'm sure they'll post when they see your post. I've loaded Weatherby magnums in past and you HAVE to follow loading data closely due to the higher pressures-they'll (pressures) jump up quickly.

RE: .257 Weatherby Magnum.
 

Nothing kooky about reloading the Roy....mine perks on H1000 and 100gr Sciroccos @ just under 3600fps.

100gr NBT's are great bullets tooand will work well on speed goats


Brett

RE: .257 Weatherby Magnum.
 

hunter5325 - Did you try other powders before choosing H1000. I load H4831SC for my 7mm Rem Mag and was gonna start with that. I was also considering H1000 or Retumbo. It is really difficult to find powder around here right now, especially anything designed for magnum/overbore rifle cartridges.

RE: .257 Weatherby Magnum.
 

I've ran a bit of H4831 in my Roy with 100's and found it to be very consistant, however I found it's velocities trailed those of H1000, Retumbo, and R25 by a good 100fps or so with the various 100's I tried.

As a side note I found that though Retumbo is slower than H1000 they both maxed at the same charge weightwith similar velocities. In my 300Rum the difference between the two powders is much more noticeable.

I would say H4831 would be a very solid powder to start and maybe end with...


Brett

RE: .257 Weatherby Magnum.
 

I think I am going to try H1000 or Retumbo because I also recently purchased a .300 Wby Mag that I will load for eventually and one of those will probably work well in it too. Now I just have to find someplace to buy it!

What charge are you using with the H1000?

RE: .257 Weatherby Magnum.
 

I worked up to 75grs with the Swifts

As a side note my go-to powder in my 300Roy is H4831...

RE: .257 Weatherby Magnum.
 

Brett - That is interesting about the H4831 in your .300 Wby. I have always found it incredibly consistent in my 7mm Rem Mag. Without failH4831 gives me the best velocities and the best groups no matter which bullet/weight I feed my 7mm. I think I am going to give H1000 a try with the .257 Wby. My brother-in-law has been getting pretty good accuracy results with R22 in his .257, but none of the loads have been over a chrony.

RE: .257 Weatherby Magnum.
 

I've not had too much experience with my the 257 Wby, yet, but so far I've had great luck with 100 grain Barnes Tipped TSX bullets with IMR-7828. I have a Remington M700 LSS Limited that shoots just under 1/2" at 100 yards with that bullet and 71.0 grains of IMR-7828. Don't know the velocity and I really don't care because of the great accuracy. The books say this should be running in the 3500fps ballpark and is at or near MAX LOAD depending on the source of the data, and I have no pressure signs in my rifle. All I do know is that when that TSX goes though a deer's heart, it's not going to matter if it left the barrel at 3450 or 3550 fps, 'cause the deer is going down just as fast either way. Accuracy is WAY more important that raw speed, IMO, though the 257 Roy has plenty of the latter just by its nature.

I've also got a load workup started with 7828 and 110gr Nosler Accubonds which I've loaded but have yet to shoot.

I am also not using .257 Wby cases (important note). At the time .257 Wby brass was not available, so I bought .270 Wby brass and necked them down with excellent results. I've also had some very promising results with reformed 7mm Rem Mag brass, with fire-forming loads running sub-MOA (though just barely).

I just used the last of my IMR-7828, so I need to try to find some more and rework the load (lot numbers won't be the same). Given that I'll have to rework the load anyway, I've been considering trying RL-25, H-1000 or even Retumbo, depending on what's available. I haven't seen a lot of Retumbo data for the 257 Roy, but its burn rate suggests it might have good potential with heavier bullets in the 110-120 grain range.

Mike

RE: .257 Weatherby Magnum.
 

These are pics from the initial load workup. The data is as written on the target.

Mike