The Hodgdon Youth Data site shows 41.2 grs of H4895 with a 120 gr bullet for the 7MM Remington Mag. It does not show a load for the .257 Wby Mag although the cases are almost identical. And you can also shoot a 120 gr bullet in the Wby. The case capacity for the Wby is 5.51 cc and the capacity for the 7MM is 5.27 cc. Why couldn't you use 41 grains of H4895 in the 257 Wby with a 120 grain bullet?

What you are not compensating for is the smaller bore diameter of the 257. The smaller bore does not allow for pressure disipation as fast as the .284 bore. The load you mention will be fine with a 100gr bullet in the 257.

I use quickload to try and keep me on good track when playing with these ideas. This is the way I would approach it.
According to QL the 41.2/7mm/120 bullet scenerio produces a 60% fill and 25k pressure.
I have read in the past that a near 65% fill is pretty optimum for H4895 but can't say where I've read it.
Using QL...if it were me...to be a little more safe I'd get closer to a 65% fill to make sure of more conistant ignition.
This would be a projection for a 257 that I would probably start at. 45.0 grains==63% fill==35k pressure==close to 2825 fps in a 26" barrel.
I would go to the range and try accuracy and chrono the load...you could work up from there a grain at a time for more accuracy if needed.

Being just a little more gutless than kracky I would start at 41gr.4895. That should put you in the 250-3000 ball park.

In the 25-06, the max. recommended load for the 120gr. bullet is 40gr. of H4895 at 61400 PSI.

In the long throated Weatherby that same load should yeild less than 47000 PSI.and give you room to safely work up.

I seriously doubt if kracky's recommended starting load of 44 grains will get you into trouble but loading 2 or 3 rounds lighter can't hurt either. roger

OOPS--i realize I didn't make clear my data in QL was for a 100 grain .257 bullet.

If you want to use IMR 4064 the Speer #13 manual gives a loading of 48 gr at 2613 to 52 gr at 2864. If you want a really reduced load get some SR 4759.

Rad

HerrMesser thanks for the reply. I'll probably give the IMR 4064 a try.

Well, I finally got around to working up a load for my .257 Wby Mag (Vanguard) using 39 grains of H4895 with the Hornady 117 Interlock bullet. THIS IS ABSOLUTELY THE BEST GROUPING LOAD I've ever developed for anything.

The day I shot, it was really windy so we set up for 60 yards. I fired a couple of shots with what looked to be only one hitting the paper. I shot again and the same thing, but my buddy, looking through the spotting scope, said it looked like the hole was getting a little larger. I shot a 4th shot at a different target and it was indeed hitting the target at exactly the same place the others were hitting. I WAS SHOOTING ONE HOLE.

I'm in the process of moving or I'd post a photo of the group. (I'm using my old computer with no scanner to make this post.) I shot it the other day at 100 yds, and it was again very windy, but the holes were almost touching. This is a tremendous reduced load for my gun--extremely fun to shoot.

Thanks to all for your help, especially Roger!

P.S. I'm guessing the velocity is around 2500 to 2600, but have to chrono to verify. Anyone have any software that'll give a little better guess.

I have reduced 4895 and reduced it to half charges and never found the bottom. Reduced charges like fast powder and heavy lead bullets.

Congrats on finding a perfect load right off the bat.....that doesn't happen often. According to QL it says the load has 56% fill, is at 29,300psi and predicts 2407 vel. You are below hodgdons recomendation of 60% fill so if you get any signs of a delayed ignition I would say you should get more fill into that case.
Let us know how close the prediction is....you could actually be a tad slower if you have lots of freebore cause QL doesn't factor that in.

quote:

Originally posted by Red C.:
Well, I finally got around to working up a load for my .257 Wby Mag (Vanguard) using 39 grains of H4895 with the Hornady 117 Interlock bullet. THIS IS ABSOLUTELY THE BEST GROUPING LOAD I've ever developed for anything.
P.S. I'm guessing the velocity is around 2500 to 2600, but have to chrono to verify. Anyone have any software that'll give a little better guess.

Good on ya ,Red C. The velocity is probably closer to 2300 fps. roger