Home Forums Hunting & Shooting Custom Rifles & Wildcats 375 Ruger & .416 Ruger to .358cal... neck length the same?

If one was to neck .375 Ruger and .416 Ruger case to .358cal what would be the final neck lengths for each?

Im hoping for at least .350"

You can get that neck length, but I think you will have to push the shoulder back a bit. Drawings I found show the .416 with a .340" neck and the .375 is at .305". Simply necking the .375 to .358 should end up with a shorter neck length than what you started with.

You might be farther ahead to make up a 35 Newton, and form cases from the 375 Rugers, with a trimming. The Newton is 2.5 inches and the Ruger is 2.6 inches. I neck full length 338 RUM, virgin cases out to .356" to put in false shoulders, before loading them as .338's. So both the 338 RUM and the 338 Win. Mag. cases will neck up without too much trouble, using Hornady elliptical expanders.

Both of these can be done as 2R chambers. You use the factory 338 finish reamer and its stock GO gauge, and then have your G.S. neck throat ream with one of his own set to make the 2 Reamer chamber. This way you use the stock factory's GO gauge, be it belted or rimless. The 35 Ruger would also require a custom GO gauge, somewhat shorter than the stock 375 Ruger's.

That 35 x 338 RUM is one really bad looking case, IMO! But the smaller diameter 375 Ruger rimless case will feed better in many more actions.

YMMV but IME necking down lengthens the neck while necking up a case shortens the neck of the original case.

if your goal is to minimize the lengthening of the neck in forming the 358 case, then starting with the 375 rather than the 416 will probably get you there.