DF: is there any particular 257 diameter Hammer bullet that you would recommend? 10" twist. Thanks
I've not tried the Hammer in my Roberts.
The 178 out of my .358 Win Pre-64 M-70 FWT performed very well last Fall on a WT. Great expansion, quick kill. And, they are accurate.
If I was going in that direction with the.257R, I'd try this one. https://hammerbullets.com/product/257-cal-90g-absolute-hammer/
With their patented low friction bullet bands, they'll fly faster than conventional bullets. So, you could probably get some really impressive velocity out of the Roberts.
The Hammer owners are engaged and very helpful. It's a small enough company to get personalized attention. They may have loads for that bullet. Give'em a call.