Years ago I loaded some 458 Winchester magnum rounds and full length resized them. I had been told that with belted brass one should always full length resize. Is this true or can one neck size only? I have found with my reloads that neck sizing only improves accuracy. I will soon have a 375 H&H and do not have alot of experience with belted brass. What tricks are there to belted brass resizing? I plan to shoot cast as well in it and think neck sizing would in my mind be the way to go. I would appreciate your input.

Thanks Alot: Leon

Without a shoulder, the only thing headspacing the .458WM would be the case taper and that belt. Without a shoulder to worry about setting back, I'd just size until chambering was free and easy and go with that.

In fact, of all the belted cases, the .458 has the best reasoning for that belt.

IF using for "serious work" (which seems more likely with a .458) would use new or once fired cases, full length sized, and not worry so much about case life or 1/4" of accuracy as I would be about whatever's trying to chew on me.

I "3/4" size my .300 WM and .338 WM brass. In other words I size it so it chambers smoothly into my rifle, but not enough to completely set back the shoulder. To do this I bring the press ram to full up, and screw the sizing die all the way down until it meets, then back it off about an 1/8 of an inch, or the thickness of a nickel. I then size one case and check the fit of the case in my rifle. If it doesn't chamber easily, I resize again after turning the die down 1/2 turn. I do this until it feeds and chambers easily, but has a slight bit of resistance while closing the bolt. I then lock the ring at that point, and resize all the rest of my brass. This works well for me, and it's how I've been doing my hunting ammo for years with no problems.

Gents,

I neck size for the 7mm Rem Mag, and have had no troubles thus far. Accuracy is excellent, although I am not sure to what measure the reloading precedure contributes.

One thing that I am told, but have not verified, is that neck sized rounds are rifle specific, and that they may not work safely in any other rifle.

No problem for me, as I only have the one.

Good shooting.

Steve

Neck-sized .458 Win Mag cases with a carbide .45 Auto die, once, before I had the correct dies.

Works pretty slick!

The .458 being an exception, I set up any other bottleneck case so that the shoulder is pushed back a couple of thousandths of an inch by the full-length sizing die, and ignore any rim/belt, basically.

The brass will last longer, be easier to size, and in theory should fit the chamber better.

A tool like the RCBS Precision Mic is invaluable in setting up dies for max brass life.

Personally, I do not find better accuracy with neck-sized brass. Seems to me that pure neck-sizing doesn't necessarily leave the neck concentric with the case body.