I love my custom 257. It is an absolute tack driver. Shooting quarter inch groups at 100yrds. One benefit of you having reloaded for the 7mm mag. You can use the brass for your 257. You will have to run it through a full length sizing die, and cam it over a few times. Thats what I do...buy once fired 7mm rem mag, and neck it down to 257 wby. It will be a little short compared to 257 wby brass, but dont let that scare you.

If you are going to rebarrel your action to 257wby. You need to call pacific tool and guage and order a custom chamber reamer. Factory wby chambers have a lot of free bore, and do not allow you to load to the lans. PTG can even tailor your custom chamber reamer to a specific bullet you want to shoot. I had mine tailored for the 115 VLD, but the left just enough room for me to shoot barnes and noslers in the 100-110gr. I ordered an un chambered barrel from krieger, and had it sent to my gunsmith. Had the chamber reamer sent to him as well. He has a deal where if you let him keep the reamer, he will pay for half the cost of it. Not sure exactly where you are located, but if you used my gunsmith, he has that reamer...so that would save you a few dollars.

If you have any more questions, give me a shout.