Reloading for my .375. Have many once fired
Federal cases. Is there a difference in case capacity of the Federal compared to Remington or Winchester, and would they effect the amount of the powder charge?

Yes,there very well could be. The manufactures have to meet a SAMI standard but that does not mean all hold the same amount of water.
I always check a new batch and keep them separated if there is a difference of one grain or more.
As for the loads and how they perform you can get yourself into trouble quickly if the case has a smaller capacity than the others and you are using a max load.
If the case is larger in capacity you will get a lower pressure and the bullet will drop under your target or radically change your point of aim to hit the target.
A few minutes doing the water test saves problems at the range.

Yes there is which is why I separate them and keep all of one make together; this does not mean that I use different loads for each; just that they will produce different pressures, velocities, and should not be shot into the same group. You don't really need to do a water test; just weigh them and you will see. The outside is the same isn't it?
Now, if you are up against very max pressures, then you have to watch the heavy cases as they, obviously, have less internal capacity.
And if you are after a certain velocity, then you want to check that; I just load for accuracy and don't care about 50 fps or so.
I do not separate hunting brass to within one grain; that is overkill for me. I only separate buy make and age.

Just weighed some;
R-P 262.1
R-P Nickel; 261.6
WW; 252.3
FC Nickel; 268

I had thought to take dpcd weights and adjust volume based on weight difference. I failed to adjust for the density difference as 900 ss pointed out. So I started over.

Anyway looking at QL and using the 300Wmag simply because QL listed several brands of cases with volume ranging from 87 to 93.8 a 62,000 load in the larger case is a 77,000 load in the smaller.

Point to be made if you aren't pushing max then changing brass brands might only result in poor accuracy and velocity variation. If your happen to be at or above the limit with larger capacity brass and grab a smaller capacity brand you can get into pressure trouble.

There has been warning for years about simply substituting Lake City brass for example.

Brass weighs 8,5 times more than water. The difference is less than two grains water between the two extremes, and thats not 6% volume.

quote:

Originally posted by 900 SS:
Brass weighs 8,5 times more than water. The difference is less than two grains water between the two extremes, and thats not 6% volume.

Very good point, 900 SS.

Another point which is overlooked: The relative volumes of two unfired cases is somewhat meaningless. It is the chamber of the gun which is the pressure vessel and its volume, not that of the unfired case, determines how much space there is in which to burn powder (along with the variable volume of the bore).

In fact, it is possible for a heavier case to have greater internal volume than a lighter case, depending on how much of the mass of the case is in the head and the dimensions and shape of the head (and rim).

Bottom line: Yes, cases of different makes, and even different lots of the same make, can yield different performance. That's why it is advisable to segregate cases. But it is not possible to consistently predict how the different weight (mass) of different cases will affect pressure and velocity.

All true, which is why I pay no attention to it; just segregating cases by brand but not changing loads.
I suppose I could actually put water in the cases if anyone is interested.

I compared the max powder capacity (filled to the very top) of a 375 H&H case from Norma and ASquare. I was using Norma 203B. The Norma case held 89 grs, the Asquare case 90 grs.

I mix my 375H&H cases. 300 grainers with 203b loaded to around 2500fps and using iron sights, no problems.

Maybe I should check this over the crohronograph. I would be interesting to look at groups with mixed and non mixed cases as well, but I wont bother putting on a scope and I dont have a lot of different cases for my other rifles.

I also mix 38spl cases and you need a Ransom rest and a lot of rounds to prove anything statistically. I think.

quote:

Maybe I should check this over the crohronograph. I would be interesting to look at groups with mixed and non mixed cases as well, but I wont bother putting on a scope and I dont have a lot of different cases for my other rifles.

If you like your groups and have no issues why worry about it. As to pistol cases only my 44mag and 45acp are grouped by brand. I push those. 38, 380, 9mm etc are a mixed batch.