I had (passed on to son) Ruger .257 Roberts "Centennial Model), that had so much free-bore I could not find a bullet long enough to get anywhere near the lands. I only used hand loads in it, and never saw any signs of pressure no matter how high I went with the loads. However, accuracy with that rifle was dismal (about 1-1/2" to 2 inch groups were the best I could get), but good enough for deer.
It was often said that the reason that the .257 was not more popular in the old days was that the rifles chambered for it were too short-throated to accept the longer bullets for deer. So I suspect the Ruger dealt with that in an excessive fashion.