SmallCaliberCentral

Is there any reason to re-size brand new Winchester brass? I will naturally trim them.

as long as the case mouth isn't dented or out of round you can get away without sizing them. To be honest i wouldn't trim them until after the first firing.

On any new brass, it's best to at least neck size it before trying to load any bullets. By neck sizing, you'll make the neck perfectly round to properly hold a bullet with the correct neck tension; new brass has neck tension varying all over the map if left un-sized. If you look at the mouths of new cases right out of the bag under about 10X magnification, you'll wonder why you ever asked the question.

Once sized, do the inside neck chamfer and outside deburr, then trim after first firing, as they'll all change length...some will actually get shorter, some longer. It makes no sense whatever to trim brand new brass before it's been fired....it'll fit your chamber okay right out of the bag if it's a factory barrel, but be sure to at least size/chamfer before loading (F/L size if it's an autoloader).

(Once you get up to speed, you'll most likely uniform primer pockets, deburr flash holes, then neck or F/L size before the brass ever sees a rifle chamber. )

mvpal wrote:Is there any reason to re-size brand new Winchester brass? I will naturally trim them.

It is best to neck size them, then check for length (most often new brass will be just fine), camfer the inside and outside of the mouth and proceed with reloading. New brass is most always within the range to load with no problems, the first time. From then on I only check for length, trim to length and/or square up the mouth, and neck size from then on, till the case gives out. In my opinion you will get optimum use out of each case. Case life will vary depending on the powder charge you are using. Near min or up to full max loads. Bill K