Me too, but it would NOT be a factory load. The .257 has fallen from grace pretty badly (due to no fault of the cartridg4e at all), and it seems to me that the factories are not putting much effort into marketing really accurate ammo for it much these days. You don't say what load you have tried - what bullet weight, etc. It is quite possible that some particular bullet type and weight will work better for you. (BTW, I have had some pretty great accuracy from handloads using Rem Core-Lokt bullets - but I have never used any of these for game!)

I'd follow noKnees' advice. Make sure the bore is totally cleaned, and all screws everywhere are tight. A great number of things, besides bad ammo, could be causing your problem. And most of them can be easily fixed or eliminated......