My rifle is the Ruger Gunsite in 308 W and I have a fairly good mix of once fired cases, some already loaded and some waiting to be loaded. What is interesting is how much variation there is in both the weight and capacity of the cases. Winchester brass is the lightest and has the most capacity. Next down the list is Remington. Finally there is Federal and Lake City, which IMO is all made by Federal because the weights and volumes are identical. Following is the breakdown.
BTW, Nevada Ed's advice about backing loads down is quite sound. There is enough difference in volume that a load that is compressed in a Lake City case will rattle slightly in a Winchester Case.
I have about 100 once fired Lake City cases in 308 Winchester. Also have 12 Lake City Match cases. The standard LC runs 178.4 grains +/- about 0.7 grains with a strong tendency to cluster at 178.4 grains. Meaning the Standard Deviation of the weight is quite low. As for LC Match, every single one of those casings weigh 178.5 grains. There is no variation in weight at all that I could detect. BTW, all of these casings have been trimmed.
Now where it gets interesting is that I also have 60 or 70 Federal cases and they are IDENTICAL to the Lake City Cases in weight. Based on this I believe that it's safe to assume that the Lake City cases are made by Federal.
Also have some R-P cases, which weigh in in the range of 163 grains and Winchester cases run around 154 grains as I recall. Unfortunately all of my Winchester cases are loaded so I can't get a more exact weight until I shoot some off.
Personally I haven't had any issues or concerns about using once fired brass. In my case it's all come from Police ranges instead of military bases, thus the variation in headstamps. However, if you sort the brass by headstamp and use a bit of common sense when loading it all works just fine.