Sizing New Brass...Yes or No?

[Timothy]

I use Starline pistol brass almost exclusively and, upon the advice of others, have been sizing new brass. The other day I asked myself why I was doing this. New out of the box Starline brass when loaded without sizing poses no chambering problems but I wondered about bullet grip. For instance, a Berry’s coated 9mm bullet measures .356 and my expander/flaring die expands the case to .351. (Not counting the flare) This leaves .005 of squeeze on the bullet during seating. The new brass comes through at around .348 so I’m expanding it .003 to .351. Now if I size the brass first it is about .347 and the expander die stretches it out .004 to .351.
In my feeble mind a .351 case opening puts the same amount of tension on a bullet regardless of what dimension that opening was to start with.
Do you agree and find NO reason to size new brass as long as the diameter of the mouth is less than the diameter of your expander die?
Remember, I’m talking new brass here.

 

[Steve Smith]

As far as handgun, yes, you're fine. With rifle, and specifically precision rifle ammo, you want to ensure the concentricity of your brass by running it through your quality sizing die.

 

[Black Snowman]

I sized my 10mm Starline when I got it for 2 reasons - so when I developed my load in them my crimp/case grip on the bullet would be the same and I was putting most of them through the progressive anyway and why take the time to remove the die. It wasn't going to work the brass much anyway.

That was my thinking, YMMV and all that rot.

 

[Gewehr98]

Yes, as a matter of procedure.

Stuff gets shipped to my front door, and banged up quite a bit, case mouths out-of-round, etc. I have carbide dies for my pistol rounds, and I bell the case mouths via the Dillon anyway, so it gets resized once it's put in station #1.

Rifle brass really takes a beating in shipping. I'll have to take some digicam pics of a box of nickel-plated .300 Savage brass I got a few years ago. Looks like it came to me from Remington via Madagascar!

 

[tc300mag1]

I size it all as some of it looks like they were ran over by a truck . My ups man is rough on packages

 

[HSMITH]

Size it all when new. Search this topic, a lengthy discussion was held a while back on this exact thing.

 

[JoeHatley]

Yup, I size all mine. I've found that even the new stuff needs it.

Joe

 

[Cal4D4]

I've had good luck using unsized Starline in 10mm. Just got a new batch and sizing tightens up the cases a few thou. Couldn't hurt.

 

[g56]

I've got a bunch of virgin Starline 45 ACP, I've loaded part of it, and I ran it through the sizer die, for uniformity if nothing else.

 

[C1PNR]

All new rifle stuff gets sized, trimmed, and case mouth chamferred. Then load.

Pistol all goes through the carbide size die on the Dillon at station 1.

 

[Quantrill]

Yes. Size it. Quantrill

 

[stans]

I resize new brass.

 

[ocabj]

The only brass I buy new and unprimed is Lapua in 308. I don't resize. I usually run a flashhole deburring tool to make sure the flashhole is clean, but that's about it.

I had one box of Lapua that had dinged necks that weren't perfectly concentric, so I neck sized them.