NOTE: I also have this posted over in the Small Caliber section as well, so don't answer it twice.

My son has a new .257 Wby Mag (Vanguard) and the ammo that shoots well in mine and my son-in-law's will not group well in his. We've been using RL22 with Hornady 117 grain interlocks and mine also shoots the 100 grain Sierra GameKings real well. I've tried a number of different charge weights with this two bullets but can only get about 1.5" groups at 100 yds. Mine and my son-in-law's shoots sub MOA. If you were going to try a different powder, what would be your first choice, H or IMR 4831? I'm thinking it is more of a powder problem than a bullet problem since it won't shoot the Hornady or Sierras very well; however, if you were going to try a different bullet, what would it be? I'm looking for tight groups and am not particularly worried about speed, as almost all loads for the .257 Wby Mag have plenty of speed for our whitetail deer in SE Oklahoma. Your advice will be deeply appreciated.

Red

I had good results with 68.0 grains of IMR 4831 and 115 grain Nosler Partition in a Mark V.
I wad getting 3/4" groups @ 100 yards with three shots.

Good Luck

Steve

My S-I-L has a Weatherby MarkV "hand select" 257Weatherby that is 30 Y.O. that used to be his step-father's rifle. We tried different powders and bullets and it would only shoot about 2" at 100yds on a good day. I thought the barrel was showing signs of neglect and didn't think it capable of any better accuracy. I have a 25/06Rem that wouldn't group until I tried the Speer 120 grain BTSP bullet in it and it shot into .5". I recommended he try that bullet with H1000 powder, which he did and that rifle shot into .5" also after he found the sweet spot. I don't remember the charge weight he used for this load and I don't want to get you in a jam so I suggest you do your own load developement. Good luck

I would not use RL-22, IMR 4831 or H4831. I think RL-25 and IMR 7828 are better choices.

Some older barrels, I believe, were made with a 1:12 twist and will probably not stabilize 115 gr. plus bullets well.

My 257 wby vanguard likes the 115 gr nosler ballistic tips and RL-22 powder. I know you've tried the powder, already, but try the BT's. My rifle didn't like the RL-25 or IMR 4350 that I tried, but maybe his will?

I really want to try out the new 100gr Tipped Triple Shocks from Barnes. If they're accurate over a charge of 7828 and 215M's, you should be set to go. I'd start with about 65 grains and work up.

I think I'm going to try the 7828 with bullets we've been shooting and see what difference that makes first. Then, I'm going to try the 7828 with a couple of different bullets--haven't decided which ones yet. Then, I'll try the new bullets with the RL22 we've been using. I'd really like to know if it is the powder or the bullets or a combination. I'm still open to your input and I appreciate the response to this point.