I know nothing about this rifle or its chambering but actually the416 Taylor was the 458 necked down to accept 416 bullets with specific dimensions for neck and shoulder, length and diameter. It is approximately the 338 win necked up but the two case dimensions are not the same and to neck the original 416 Taylor down to 375 or 338 will give different neck length than the 338 win. Nothing significant, but I have the drawings for the 416 Taylor and had Dave Manson make a reamer for 416,375 and then a 358 to use the same headspace gages, never made a 338, kind of redundant with the fine 338 winny but the point is a Taylor dimension case is different from the 338 win case. The neck is slightly shorter than the 338 winny and H/S gages for Taylor won't go in a 338 win chamber. I believe Dr. Ken's book reflects this also.
