How influential is different sources of brass for accuracy?

[His lordship.]

Back when I handloaded centerfire rifles I usually went with Winchester or Remington for my brass sources.  Used some Federal too, and with my exotic calibers, Norma.  I remember the Remington brass being a bit stiff.  I felt that the greatest influence on handloading was the choice of bullets and powder amounts, I used different primer brands, more for variety reasons than any assumed accuracy issues.
 
Got started recently in handloading for .45 long colt.  Have been using Starline brass, and experimenting with the 200 and 250 grain bullets, have not used jacket bullets yet.  Shot some 200 grainers in Magtech brass that I had,  the accuracy was very inconsistant.  Often the bullets would go all over the paper, or off of it.  Then I would get 3 shots that would be very close.  Can different brass be that influencial with accuracy in handloading?  I never understood why some shooters said that different primer brands would effect things too?

[bulletstuffer]

I asked my buddy the same question today coming back from the range.  I just separated brass by manufacturer and will be giving that a try.  This should be interesting
 
Bulletstuffer

[MZ5]

I was contemplating a (joking) reply about how brass forged in the Western USA is far superior to that forged in some other Hemisphere, but I'll lay off that (for now). 

Certainly the brass can make a difference.  Harder or softer brass will grip and release the bullets differently, and cases which are not concentric in the neck area will also impact the release of the bullet, and sealing of the chamber as pressure builds.  Whether these things affect your accuracy enough for you to notice depends upon a number of things.

I don't sort brass by headstamp, except/unless I know there's a significant difference.  Here's an example:  I had to sort out a particular lot of PMC 45 auto brass from _all_ my other 45 auto brass, because it would buckle the mouth during the seating stage (on my progressive) every single time, unless I adjusted my charging/expander die.  That's doesn't work in the middle of a big batch of reloads.  It also had significantly different internal volume/capacity; enough to alter pressure enough to mess with how my pistol shot.  It wasn't even _all_ PMC brass, just that one lot.  The headstamp was just enough different that I could identify and separate it (I took it to the recycler, actually).

[Snowshoe]

I have seen huge variations in the weight of brass, and the outside size is the same, so the inside size must vary. When shooting .30-30 rounds at the range one time I had the brass weight marked on each load. I saw hits as much as 2" higher with the heavier brass. It opened my eyes.

[jhalcott]

 Yes brass weight can cause big differences in performance! A powder charge in a LIGHT case CAN be an over load in a HEAVY case.I have 5.56 brass that weighs 86 grains and with my preferred load is very accurate. A friend gave me some Sako surplus ammo that seemed HOT in his AR and MY Rem.700. I pulled the bullets and found case weights from 96 to 110 grains. My preferred load would not fit in those cases! Another thing with brass is the hardness of the brass, this can be due to repeated firing or the metal alloy itself. This will cause inconsistent release of the bullet. MY plinking ammo is what ever I can get or scrounge at the range. Target and varmint ammo is a bit different. That is selected cases from KNOWN sources.