Load Development New Brass

[Vinny]

New to reloading. I have new brass and I plan on reusing Federal brass from ammo I will be using shortly.
I’ve read that a starting loads should be used for new brass. How does this equate when reusing brass from factory ammo that is clearly not starting loads.
Doesn't factory ammo use new brass?
TIA

 

[wapitibob]

I use virgin brass, full loads, just plinking to get it shot. I then did load dev with that once fired brass. The shoulder is .002 off the chamber after 1st firing so it's close enough for load dev.

 

[Vinny]

I use virgin brass, full loads, just plinking to get it shot. I then did load dev with that once fired brass. The shoulder is .002 off the chamber after 1st firing so it's close enough for load dev.

Appreciate the reply and the info, thank you.

 

[billydonk]

My new brass seems to take few firings before it stops "stretching" in a particular chamber.

 

[Wrench]

The theory is the case head can work harden before it stretches. If it's been shot full zoot, there's no reason to pussy foot around. Do start with reasonable charge weights....because it's good practice.

 

[Vinny]

Appreciate the advise. So apart from the charge, I assume the amount of ‘stretch’ will also depend on caliber and brass quality? Right?

 

[Wrench]

It's mostly to control primer pockets. There's no good way to tighten a pocket, but if the case head can harden, it lasts longer. Perhaps there's a level of voodoo or bs there, but guys who get a ton of loadings do this.

 

[wapitibob]

First firing on nosler 7stw brass stretches .017-.018 in this barrel.

 

[N2TRKYS]

I develop loads using virgin brass(I never start at the starting load). I never had a problem with once fired brass not replicating the virgin brass load accuracy with the same load. Don’t overthink it.

 

[wind gypsy]

New to reloading. I have new brass and I plan on reusing Federal brass from ammo I will be using shortly.
I’ve read that a starting loads should be used for new brass. How does this equate when reusing brass from factory ammo that is clearly not starting loads.
Doesn't factory ammo use new brass?
TIA

There is multiple factors at play here.

If your virgin brass isn't the same (brand and even manufacturing run in some cases) as the fired brass, there is a good chance that they will build different amounts of pressure at the same powder charges. Brass volume (and in turn, safe powder charges) can vary greatly between different brands of brass. In 300 WM for example, you might be able to have powder charges differ by 6 grains to get the same pressure in different brass because of the vast differences in case volume between manufacturers.

Also, virgin and fired brass from the same lot might build pressure differently at the same powder charges.

My experience is that a fired case that is sized for only minimum chamber clearance to reliably feed will typically show higher velocities and pressure signs earlier than a virgin case from the same lot. I've seen it explained that some of the energy goes into expanding the case rather than propelling the bullet.

In theory, "starting loads" should be used any time a new unknown combo is used but you'll come to find out that "starting loads" in a reloading manual isn't always a great reference but that's a rabbit hole I'll leave alone.

If I understand the point of your question correctly, my advice would be to look at a safe starting powder charge as being the same whether it's fired factory brass or virgin brass.

 

[Harvey_NW]

I’ve read that a starting loads should be used for new brass. How does this equate when reusing brass from factory ammo that is clearly not starting loads.
Doesn't factory ammo use new brass?

Yes they use new brass. The difference is that it's at a SAAMI spec charge that will be safe in every chamber out there, so not hot. The way I understand it virgin brass with chamber space fired at high pressures causes the brass to expand in places you don't want it to (like the primer pocket and web area), and hardens the case head upon firing, ultimately hardening the pocket in it's slightly expanded form. The only way to correctly and fully form a case first firing is to seat the case head against the bolt face either by false shoulder or by jamming the lands, in which case typically lower charges are used to reduce pressure spikes.

I've been researching the topic myself lately because I built a custom chambered rifle (7 Sherman Max) that was marketed as having "fully formed brass available, non fireforming wildcat", and have recently seen a lot of people with feedback saying they loaded as per usual and are only getting 1 firing out of brass and the pockets are toast. Turns out between wear on brass mandrels and reamer specs heading a tad bit north and south of each other, it's now a true fireform combo, and the guys that are properly forming are getting expected brass life.

So depending on brass, chamber dimensions, and life expectancy, I've seen enough evidence from the current situation I'm in to believe that there's some proof to the matter.

 

[Wrench]

With good brass, good luck and good techniques it's possible to get 20 loadings on brass.

Hot rod it from the package and you could loosen pockets in a loading or two.