Size new brass or not

[charles p]

It just cleaned up the primer holes and pockets on some new Winchester 7mm-08 brass.  Does it need sizing or can I add a primer, powder and stick a bullet in it?

[TNrifleman]

I've always found it a good practice to size new brass. I also trim new cases to a standard length and chamfer the case mouths inside and out before loading.

[bigjeepman]

I do the same as TNrifleman ... measure your new brass after sizing and see what the length is. I just did this with new .308 brass and I had to separate and trim quite a few of them. Some were undersized too. It isn't that much extra work and you start off with new brass that is good to go.

[PaulS]

Looks like we have a consensus. Size those new cases - they have been tossed around and you can't be sure that they are straight.full length size them the first time. After that neck size them only so they fill that chamber.

[beemanbeme]

Wahl, somebody's got to be different.  If you trim your brass to length before its first firing, it will be all sorts of different lenghts afterwards.
I do as little as possible to new brass.  I make sure it will chamber (I've never had any that wouldn't unless its a custom chamber and that's a different story); I bump the resizing ball of the die thru the neck to round it up; I chamfer the inside of the neck (if I'm using boat tail bullets, I might not do that); then I prime 'em, charge 'em and shoot 'em.  THEN, I find the shortest case and trim them all to that length or the recommended trim length from a manual, whichever is shorter and chamfer the inside of the necks and deburr the outside and uniform the primer pockets if I'm gonna do that and weight sort them, etc. 
In other words, fire forming is my first step in case prep.

[Catfish]

It`s a good idea to size your new brass, because you never know when a batch of new brass will have one that won`t chamber for some reason. I rearly do anything with the primer pockets or the flash holes. If the hole look good, they are, unless I`m preping brass for bench rest shooting.  I never trim brass untill it`s been fire formed, unless the brass is perfectly uniform the cases will be different lenths after you fire form and be just as far out as when you started the first time. This is especlially true when forming wildcat brass.

[longwinters]

+1

Long

[Ahab]

Wahl, somebody's got to be different.  If you trim your brass to length before its first firing, it will be all sorts of different lenghts afterwards.
I do as little as possible to new brass.  I make sure it will chamber (I've never had any that wouldn't unless its a custom chamber and that's a different story); I bump the resizing ball of the die thru the neck to round it up; I chamfer the inside of the neck (if I'm using boat tail bullets, I might not do that); then I prime 'em, charge 'em and shoot 'em.  THEN, I find the shortest case and trim them all to that length or the recommended trim length from a manual, whichever is shorter and chamfer the inside of the necks and deburr the outside and uniform the primer pockets if I'm gonna do that and weight sort them, etc. 
In other words, fire forming is my first step in case prep.

Yup, it's what I do too.

[Dand]

I got to thinking about this thread today when I started prepping some new Win 348 brass. Well its been stashed away for 6-7 years but its new in the box - 20 round boxes - not the bagged stuff.

Yes I HAD to size and trim this stuff.  Very irregular case mouths and out of round.

The bodies didn't need sizing and never contacted the die.  But quite a few took several hard but careful pulls on my press to get the expander ball (RCBS) into the case mouth.  I don't recally having factory new brass this rough before. And I had lubed the necks inside and out.

Made me wish I had the Hornady eliptical expander ball.  The RCBS ball is rather abrupt and rough. I may polish it a bit.

Next I'll trim them just enough to square off the case mouths and chamfer, then flare with an RCBS die so I can load cast bullets.  I sure wish Lyman would be willing to make me an M die for the 348 - they refused when I asked them several years ago.