Size new rifle brass or no

[Ike666]

I've got a box of new Lapua .308 brass. I've gauged it (perfect) and measured it 2.010" with little variation. It's like a virgin.

My question is, what are the arguments for and against running it through a full length sizing die before I begin to load it?

I will confess, it is a prep step I'd as soon avoid as not.

[GP100man]

It may be new but I still treat it as once fired .

But if it fits in the specs ??

Some shooters prefer shootin it 1 time before final prep steps !!

Wish I could shoot good enuff to see a difference in uniformin flash holes & turnin necks !!!!

[Jim243]

Ike

If the cases are within trim specs, I would leave them alone. However if you could neck size them only, it would provide a better more uniform hold on the bullet and improve accuracy.

I find that the Winchester 223 brass I use is a perfect fit in my gauge. I just load them up with out sizing or trimming.

[Unclenick]

The argument for doing the extra sizing is to iron out any bent case mouths and, as Jim says, get uniform neck tension, then to trim and chamfer to match. Lapua does a factory chamfer, and if the case mouths don't have any big dents in them, there is certainly no requirement that you size them. Indeed, the way they come is the way they are when the factory loads them.

The argument against sizing them is a second sizing often sets the shoulder back another couple of thousandths. Since they are already at minimum shoulder position, that causes the new round to have extra headspace so the cases stretch more on the first firing, exaggerating the pressure ring and potentially shortening case life.

Glen Zediker says a lot of his mouse gun match loads used to be (when you could get them) in factory primed Winchester cases. I followed his example for a number of years. No sizing there, either. He owns a Sinclair type expander mandrel die, IIRC, which I also got a copy of. These have undersize mandrels standard for setting up neck turning. The mandrels have a long taper, so one of those does just fine for dented mouth straightening without the extra sizing being done. But Jim's suggestion of neck sizing, if done on the inexpensive Lee Collet Die, would accomplish the same thing. Just don't decap any primed cases with it.

[Ike666]

Thanks guys - some good food for thought.

I've got a K&M Mandrel and will use it to take care of any dents. Being the lazy SOB I am, I'm leaning to loading as is.

I think the most convincing rationale is the shoulder set-back. I don't really want to mess with the headspace.

[44 AMP]

With long straight cases, like the .45-70 and .458, I have found virgin brass with dents and out of round case mouths, straight from he factory bag. Not many, but some, so I check all and size them anyway. No shoulder to worry about on those cases.

I would neck size your brass, for uniformity. Or just use it as is, for any less than match/trophy hunt use.

[dawico]

I use that same brass, and I haven't had any trouble shooting it new without sizing it first.

[TXGunNut]

I'd load it up. Lapua cases are probably formed on better dies than we can buy so unless it was handled roughly after it left the plant it should be as good as you can get. I'd measure the inside of the case mouth and check for roundness but sounds good to me.
Could even try 10 each way, could be interesting. Let us know.
I buy RP cases packed in a bag and I'm not sure sizing them is worth my time but I do. Case mouths are occasionally a bit egg-shaped after being handled, packed and shipped a few times.
I remember the factory primed cases, Unclenick. Used some in a pistol caliber, IIRC. Ever figure out why they did so well?

[wingman]

I use Laupa brass 223 cal load and shoot can't say enough how good it is.!

[FrankenMauser]

I sometimes neck size new brass, but never full length size. It all depends on how beat up the necks and case mouths are.

Usually, I don't even neck size, even for brass that needs the attention. I just run the cases over the expander ball, and back out of the die. I've never had any issues with neck tension, using this method.

[TXGunNut]

That sounds like the best course, FM. Little doubt about uniformity with that method.

[bullspotter]

I bought 500 lapua 308 brass this summer. Talk about some nice stuff, I didnt do any prep, just loaded them up, I did do alot of measuring and such and it was good to go, Now any other new brass ive bought, winchester and remington, need to be ran though a size die, My general rule was ALWAYS size new brass period, but didnt need to with the lapua, Its top notch right out of the box.

[dahermit]

Loading to best accuracy, brand new brass should be fire-formed for your chamber and then neck sized only (for bolt actions). The first firing is just for fire-forming, the following firings are when accuracy is expected. Full length sizing is only done when absolutely required to salvage your brass.

[dlb435]

I just loaded some 243. New brass, never fired. I skipped the resize and just loaded it up. All shot with no problems. Just do it.

[mehavey]

Still, I resize/trim/chamfer even the best of new brass (e.g., my AR's .223 Lapua) for no other reasons than (A) it trues up/uniforms the neck dimensions; and (B) automatically catches any snowballs' chance of out-of-spec dimensions.

(And it doesn't hurt that I'm also doing the last too op'ns with my Giraud)
http://www.youtube.com/watch?v=SGYLmHvKVd0

....sliced bread, don'cha know...

[Snakedriver]

I know they say it's not necessary, but I can't bring myself to not run it through the sizing die anyway.

I had a batch of new .223 brass recently that despite being new "match" grade brass was way out of spec.

For me anyway, skipping steps is just asking for trouble so I go the whole route and follow the procedures.

[Doodlebugger45]

I usually size all my new brass. But I don't use the premium stuff like Lapua. On Winchester and Remington rifle brass, there's usually 2 or 3 out of 50 that really need it for damaged necks. For pistol brass, I know that Winchester .45 Colt brass definitely needs to be resized because it's way too big. I have found that for Starline and Hornady pistol brass that it's a waste of time to resize. They seem to be about perfect.

[Mike Irwin]

I always do.

It may not be necessary, but it adds hardly any time to the loading process and you're assured of all of the cases being dimensionally similar.