Resizing new brass

[elkslayer4x5]

While reading the basics of reloading in the Lyman 49th, I read a statemant that I should resize new brass, does that apply to new primed brass as well?

[jepp2]

The same reasons for sizing new un-primed brass would hold for sizing new primed brass. Removing the decapping pin would be a good start.

Most folks practice sizing new brass before loading. I check them in a Wilson cartridge gage and run the expander through the neck to make them round. The cartridge gage shows me if the shoulder is properly set on rifle brass. I don't see the benefit of running new brass through a sizing die. If it was going to be loaded ammo by the manufacturer, I don't believe they would size it again prior to loading. YMMV.

Other prep work I do is to trim to a consistent length, chamfer the inside and deburr the outside of the neck. For the best consistency I will uniform the primer pockets, deburr the flash hold and sort by weight.

[Gdawgs]

I attempted to load some new 45 Colt brass one time without resizing it. When I started seating the bullets, they basically fell right in(yes I was using the correct size bullets). I could easily push the bullets right in by hand. After going back and resizing, all was well.

[603Country]

I resize new brass before I do all the other prep work that I do. I justify the extra work by thinking that I'm starting from exactly the same baseline with each case.

[Bart B.]

Best thing it does is to uniform the neck's inside diameter and make it round. New brass mouths ain't the most consistantly shaped thing on earth.

[F. Guffey]

Nothing like measuring before and again after, then there is the fire to form, when I fire a case I eject once fired cases, others eject fire formed cases, point? Why size new cases if they are going to be formed when fired?

I determine the length of the chamber first, I then measure the length of the case from the head of the case to the its shoulder, the difference between the length of the chamber from the bolt face to the shoulder of the chamber and the length of the case from the head of the case to its shoulder determines the effect the chamber has on the case when fired.

Again, I use shoulder instead of datum, my chambers, dies and cases do not come with datums, it is up to me to furnish them, all of my datums are round holes/circles, none of my datums are lines. A popular datum is .375 thousandths (3/8”), another is .400 thousandths. Not easy for most to wrap their minds around but the 30/06 has a datum of .375, the 308 has a datum of .400, the 30/06 has both datums, .375 and .400, the 308 W has a datum of .400 and .375, point? If a reloader/smith understands what is going on they can use any number above, below or in-between as a datum as long as they choose a number between the case body/shoulder juncture and the shoulder/neck juncture.

F. Guffey

[F. Guffey]

“I'm starting from exactly the same baseline with each case”

I would suggest saving a few new cases from the lot for reference. Something like measuring before and again after, weight, diameter, case head diameter, thickness etc..

F. Guffey

[Bart B.]

Guffey asks:

Nothing like measuring before and again after, then there is the fire to form, when I fire a case I eject once fired cases, others eject fire formed cases, point?

Some folks want their new virgin cases expanded to larger dimensions than when unfired so they're closer to chamber dimensions before they resize and reload them. There's nothing wrong with this. Benchresters do this often and use an old worn out barrel to do it saving their hummers for matches.

Why size new cases if they are going to be formed when fired?

Some folks know that new cases shoot just as accurate as (sometimes more accurate than) fired then reloaded ones. But their case mouths are not all that uniform. Resizing just the neck and/or mouth makse the neck more consistantly hold bullets with the same tension as well as being very straight on the case. So they want have accurate ammo to shoot even if it's just to fire form the cases.

[ballardw]

Think about the handling that bagged brass may get before loading, dropped in a box, shelved, dropped on floor by customers, restocked, stuff on top in a shopping cart, etc... I wouldn't expect most of it to be round.

[wncchester]

"...sizing new primed brass. Removing the decapping pin would be a good start."

That seems to be a hard idea for many people to grasp tho. ??

[William T. Watts]

I'm with Guffy, I use the expanded to iron out the dings and bumps in the case mouth, uniform primer pockets, check the case length, as far as I'm concerned they are good to go. One other point many people do not know how to properly set up a sizing die for their chamber, I'll stop there.. William

[Jimro]

I've found running new brass through a sizing die to be mostly unnecessary, at least for bottleneck rifle cartridges in common calibers (308, 270, 30-06, 300 Win Mag). If the necks are dinged up pretty bad then a trip through a sizing die with expander ball is justified, but I don't bother with a lot of brass prep until the brass is literally "once fired."

Jimro