Newbie reloading questions about brass.

[BullHead]

I recently shot .533 MOA with my hand loads using regular Winchester shell casings the only thing done to these casings, neck sized, cut case length, used a Lyman flash hole deb
urring tool, lee dies and hornady concentricity gauge/tool for runout. Here comes the question...I just bought some Lapua match .308 cal. Shell casings and weighed each one the lightest being 171.5 and the heaviest being 174.9 for a total of 3.4 grain difference. I'm wondering if Winchester has a wider variance to case weight and if not am I blowing money that is not totally necessary to accuracy? If your wondering why I chose Winchester cases its simply because I had a hundred pack when I first started reloading .308.

I have seen other talks on here about different case manufacturers but never any mention that I could find on case weight variance. Does it matter if I choose to use only same weight casings and exact same weight bullets or will variances of 3.4 grains in weight not make a difference and I should stop being so anal?

 

[918v]

Winchester has about the same variance. Federal is worse.

Lapua makes cosmetically nicer brass. Lapua has 1.5 grs less water capacity than Winchester and requires about 1grs less powder to reach the same velocity. You can use that capacity difference to tune your load. For example, I developed a load for my rifle using Winchester brass that has a low ES/SD, but shoots .7 MOA. I then adjusted that load for Lapua Brass and it shoots .4 MOA still retaining that low ES/SD. I then tweaked that load for LC LR and FC10 brass by further reducing the powder charge and got the same accuracy same ES and SD. I found some LC Match brass from 1963 the other day. It has less capacity still. So I reduced the charge some more and can't wait to try it tomorrow.

 

[BullHead]

Ok so case manufacture isn't as important then as long as they are all uniform in weight or as close to same as possible?

 

[918v]

No.

Uniformity is important for ES and SD.

But ES and SD are not the only variables affecting accuracy. Note that Lapua produces better accuracy than Winchester, but has the same case weight spread.

 

[Powermac]

918v is right.
Lapua brass is produced by better machinery, and is generally more uniform.
It's also annealed, and the flash holes are very consistent as they are drilled and not punched as american brass is.
The cases also seems to last longer and stand up to high pressure better then most.

There is also some difference in the metallurgy i do not have enough knowledge to make an educated opinion about it but here is a short article.
X-Ray Spectrometry of Cartridge Brass within AccurateShooter.com

If you want other high quality brass Norma, RWS and Ruag is where i would look.
Of US made brass the expensive and prepped Nosler brass is good, and of the regular brands i've had best luck with Winchester.

And if your really anal about consistent results, you should look into H2O weighing your brass, as it will give you a accurate volume reading, as the weight of the cases is not directly transferable to volume.