I've read that different brass mfgs. hold different amounts of powder. Does this matter?? For example if one holds 50 grains of brand X (larger case) and the other holds 48.5 grains of brand X(smaller case). Both should be at the same pressure. So the bullet should travel at the same speed, everything else being equal.
Of cause one has to work up all loads.

hglass

Of course it matters. The smaller capacity case will operate at higher pressure with the same powder charge and bullet.

If you are working with relatively low intensity cartridges with moderate loads, such as the 30-30, it probably won't make any difference if you mix brass. But at the other end - high intensity cartridges with max loads- it could mean blown primers or worse.

It's a good reloading habit to seperate brass by manufacturer at a minimum and by capacity and/or lot number if possible.

Ray

Some people think it makes a difference but it is a very small difference. Just pick one that you like that fits your budget and don't sweat the small stuff.

I thought I should clarify one point. I would not buy one over another based on capacity. I would never mix manufacturers which could make a difference in pressure.

So pick your favorite company and stick with them.

Thats what you have to do. Keep all brass separate and work loads with each brand, never mix for a load.
I will never understand why they don't standardize brass capacities. Some calibers will be so close it doesn't matter but others will ruin accuracy or get you in trouble with pressure.

Since the capacities are quite different you can't expect the same results with different cases. In my 300 WinMag for instance, the max load with Winchester cases is a guaranteed overpressure in RWS cases.

depends on what kind of shooting you're doing. if the nth degree of accuracy then it does make a diff.if its just general blasting ammo then no

It does make a difference, but I think the previos posts give good info about how to pay attention and address it.

Interestingly, I recently read an article (I think on 6mm BR) that talke about a family that almost exclusively shoots the 6.5x284 in competition. One of the family members, the Wife I think, was shooting some loads that were otherwise identical to her known accuracy load, but a different type of brass {extreme accuracy we're talking here} and the groups were horrible by comparison. From benchrest accuracy one hole sort of thing, to over 2 or 3 inches or something like that. An incredible difference! I haven't ever seen such a difference, but it obviously can impact accuracy a bunch at times.......

Different brands MAY give different points of impact, I confirmed that for the 30/06 and the .222 Rem. For the latter, there are even different types of RWS brass around, the olöd one with small latters and the one they manufacture nowadays, with bigger letters.