New brass weights differ 2.3 gr for 223 shells, is that normal?

[IndianCent]

I am starting to reload 223 for accuracy (5 shot groups at 100 yards on paper). I bought new brass from Starline, Hornady and Nosler (Lapua is always out of stock). I weighted 50 rounds each, here are the results (detail attached):
Starline 93.9 to 94.9 = 1.0 grain spread.
Hornady 94.7 to 96.9 = 2.2 grain spread
Nosler 94.9 to 97.2 = 2.3 grain spread
Does the weight difference matter and if so how should I sort? Where do I draw the line? Is there an established standard weight for new, unprimed .223 Rem. brass?
Thanks for any input.

 

[spife7980]

Measure the internal volume, most of your weight discrepancy you measured is in the case head where the rims are cut that don’t effect powder capacity.

 

[straightshooter1]

I am starting to reload 223 for accuracy (5 shot groups at 100 yards on paper). I bought new brass from Starline, Hornady and Nosler (Lapua is always out of stock). I weighted 50 rounds each, here are the results (detail attached):
Starline 93.9 to 94.9 = 1.0 grain spread.
Hornady 94.7 to 96.9 = 2.2 grain spread
Nosler 94.9 to 97.2 = 2.3 grain spread
Does the weight difference matter and if so how should I sort? Where do I draw the line? Is there an established standard weight for new, unprimed .223 Rem. brass?
Thanks for any input.

While there is a correlation between case weights and case volumes, it's not a direct correlation where one weighing more than the next means it has less volume. When comparing one brand's case weights to another, as you have here, in my experience of measuring various cases those differences do tell you something about their case volumes.

Even though a case may have thicker cases heads (as spife790 points out), that often results in thinner case walls offsetting what that thicker case head might suggest. For example, I recently bought some .308 Starline cases and that has substantially thicker case heads than the Lapua and Peterson brass I measured yet the case weights was pretty virtually the same and the volumes were close to the same. Starline's thicker case head did not change the volume as some people think it should do.

How should you sort? DON'T mix those 3 headstamps. Even if you were to sort by actual case volumes, the differences in case wall thickness will effect the pressure how the bullet is held and because of differences in the brass's alloy, sizing results can vary between head stamps.

No, there's no standard weight for new, unprimed .223 Rem brass . . . or any other brass. Weights will vary from lot to lot even within the same manufacturer. That's why it's often suggested to NOT mix lots, just as you don't mix head stamps.

Here's an example from Peterson Cartridge Co. showing variances from one lot to another:

 

[IndianCent]

While there is a correlation between case weights and case volumes, it's not a direct correlation where one weighing more than the next means it has less volume. When comparing one brand's case weights to another, as you have here, in my experience of measuring various cases those differences do tell you something about their case volumes.

Even though a case may have thicker cases heads (as spife790 points out), that often results in thinner case walls offsetting what that thicker case head might suggest. For example, I recently bought some .308 Starline cases and that has substantially thicker case heads than the Lapua and Peterson brass I measured yet the case weights was pretty virtually the same and the volumes were close to the same. Starline's thicker case head did not change the volume as some people think it should do.

How should you sort? DON'T mix those 3 headstamps. Even if you were to sort by actual case volumes, the differences in case wall thickness will effect the pressure how the bullet is held and because of differences in the brass's alloy, sizing results can vary between head stamps.

No, there's no standard weight for new, unprimed .223 Rem brass . . . or any other brass. Weights will vary from lot to lot even within the same manufacturer. That's why it's often suggested to NOT mix lots, just as you don't mix head stamps.

Here's an example from Peterson Cartridge Co. showing variances from one lot to another:
View attachment 8451305

Thank you so much for the detailed explanation. I know now not to focus on empty case weight. I intended to separate headstamps but will also make sure not to mix lots with the same headstamp. I appreciate your input, it will help me to take the right steps as I go along.

 

[straightshooter1]

Thank you so much for the detailed explanation. I know now not to focus on empty case weight. I intended to separate headstamps but will also make sure not to mix lots with the same headstamp. I appreciate your input, it will help me to take the right steps as I go along.

Empty case weight can tell you something:

Take a look in that pick and note how as case weight increases, case volume decreases. Those changes in case volumes effects how one lot will perform over another lot given the same loading. . . particularly if there's a substantial difference.

One of the things I found helpful in weighing cases is to weigh the whole lot and removed the outliers (using outliers for things like cold bore, first shots). By taking the outliers out, it helped reduce my group sizes. I've done this more than once and found it helpful, like here's a box of Lapua brass I sorted by weight (just comparing those cases on each end produced a very different results):