shepdogwv

I was just wondering if anyone with a reloading book could give me some info. I was just wanting to know what the numbers are for a .257 Weatherby Mag. (117/120 gr bullet) and a .300 Weatherby Mag. (165 gr.) using the same powder and the same amount of powder. My father-in-law and I were just having a dicussion but his reloading books are at his house, and some hard numbers would be helpful. Thanks

johnny2

257 with 117 gr max 3336 fps with H 870

300 with 165 max 3305 but different powder

H-4350 FOR 257 AND 117 MV-3144 MAX

H-4350 FOR 3OO AND 165 MV-3074 MAX

bronko22000

Well its obvious that you have access to a computer and internet so why not just look up the info yourself. Just search for reload data in Yahoo or Google. Don't mean to bust you but - geez, every thing you need is at your fingertips.

CZ2506

Wait till BC hears that you're busting this guy.

eldeguello

The .30 Weatherby is a full-length case that requires quite a bit more powder to get optimum performance vs the .257 Weatherby, which is a "standard length" magnum. If you used the same powder, and loaded eaach with the bullet weights you specify, it will take alot more powder in the .300 WM. So, if you used the SAME AMOUNT of the same powder in the .300 WM, it will be WAY underloaded!

For example, using IMR 4831 (Speer manual), which is the slowest I can find that is used in both:
.257 WM with 120-grain bullet - 65 grains MAX LOAD, MV = 3199 FPS.
.300 WM with 165-grain bullet - 78 grains MAX LOAD, MV = 3142 FPS

IF I reduced the .300 WM load to the 65-grain level, same as the .257 WM here, the MV of the .300 would drop to vic. of +-2600 FPS, or less than the .308 Winchester! NOT a good idea with slow powders in big cavernous cases (ever heard of S.E.E.?? Or D.D.T.?? Deflagration to Detonation Transition.)

One Speer max load uses 89 grains of RE25 in the .300 WM with the 165-grain load, MV = 3258 FPS But this powder is too slow for the .257 WM, I guess, since there are no RE25 loads shown for it.....
Note that the SD for the 120-grain .257" bullet = .260, and for the .308" 165-grain bullet = .248.

Therefore, the 120-grain .257" bullet has more inertia, sois harder to acceleratevs the .308 165-grain bullet.....

backyardreloader

70gr, re-22, nosler 115gr, about 3300fps

backyardreloader

i use nosler 125 balistic tip 87.4 gr imr 4350 for the 300 weatherby 3700fps and very accurate. its not just a varmit load like a lot of people think. ive taken a LOT of whitetale with this load.

redgreen

257 Weatherby Magnum
Hornady 87 grain Spire Point ....IMR 7828.... 74.5 grains.... 3775 fps
Nosler 100 grain Spitzer......IMR 7828.....73.0 grains.....3655 fps
Hornady 117 grain boattail spire point......IMR 7828.....70.0 grains......3390 fps
Nosler 120 grain Spitzer.....IMR 7828.....69.0 grains.....3325 fps

300 Weatherby Magnum
Nosler 150 grain Spitzer..... IMR 7828.....89.0 grains.... 3425 fps
Nosler 180 grain Spitzer.....IMR 7828.....86.0 grains......3240 fps
Nosler 200 grain Spitzer.....IMR 7828.....83.0 grains......3065 fps
Hornady 220 grain Roundnose.....IMR 7828.....81.0 grains.....2940 fps.

**NOTE** These loads are maximum. Reduce them and work up.