brass and bullet weight differences

bcfreeman

bcfreeman

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I'm new to reloading.
I bought a couple of boxes of new Nosler brass and found that there is a weight difference of up to .5 of a grain between shells. They are factory cut to the correct lengths so trimming them isn't necessary.
Is this within normal allowable tolerances?

I bought a few boxes of Barnes 168 grain TTSX's
I weighed all of the bullets and found that there is up to .4 of a grain difference between bullets.
Is this within normal allowable tolerances?

I check my loaded rounds after they're done to compare total weights to make extra sure I didn't mess up my loading of the powder and some of them are up to almost a full grain different because of the combined brass and bullet weight differences.
At least I can tell if I screwed up with my powder weight if there is a larger difference in weights of the rounds but I still find it surprising that there isn't a more consistent weight with the brass and bullets.

I'm probably just being really anal about it. Your thoughts on this?
 
bcfreeman said:
I'm new to reloading.
I bought a couple of boxes of new Nosler brass and found that there is a weight difference of up to .5 of a grain between shells. They are factory cut to the correct lengths so trimming them isn't necessary.
Is this within normal allowable tolerances?
Click to expand...

That is excellent. Regular brass (RP, FC, WW-Super, etc.) can have a range of up to 2 grains difference in my experience (new factory brass). Unless you are doing match shooting a 0.5 grain difference isn't really a concern.

bcfreeman said:
I bought a few boxes of Barnes 168 grain TTSX's
I weighed all of the bullets and found that there is up to .4 of a grain difference between bullets.
Is this within normal allowable tolerances?
Click to expand...

Barnes TTSX's are premium projectiles so 0.4 grains seems a tad high to me. Pulled projectiles from Egyptian surplus 8x57mm I have can vary up to 1.5 grains.

Hornady usually vary only 0.2 to 0.3 grains for me but I don't measure more than 10-15 just to check; not all 100 in a box.

Again unless you are doing match shooting it isn't a concern. I don't know of match shooters that use Barnes TTSX anyway. Pretty much all match ammo is HPBT lead core.
 
For the bullets, 0.3% variation isn't bad, but if you wanted, you could sort them by weight. I doubt that you could detect differences when you shoot them.

As for the brass, the vaiation is about the same, and the results would be about the same - not noticeable. With brass however, it's the internal capacity that matters, not the weight. There's usually a relationship between the two, but two pieces of brass from the same lot can weight the same but will rarely have identical internal capacities.
 
Except for shooting long range matches, the differences you are seeing can be ignored.
Even for long range work, [1000 yards] I am happy with .3 grains brass differences and "0" difference in bullet weight.
Eagleye.
 
IMO if the brass is from the same lot just shoot it. Here is a question for you were is that extra weight? The neck or the head or the body or the shoulder.....Hope you get the idea. It's a waste of time to cull expensive new brass by weight. If you want to be accurate measure by internal volume when it has been once fired.
 
Excellent info guys! Thank you very much!
This has helped a lot. I'm going to sort my bullets for equal weight for reloading and now this leads to a new question about the internal volume.

How do I measure the internal volume of the casing?
 
I just sorted a pile of brass Saturday. All federal. I had weights ranging from 234gr to 250gr. I ended up with 44 in the 247.5gr lot. About 15 bang on 250gr, 10 249, and 2 or 3 here and there at about any weight in between.

Also for sh/ts and giggles I measured capacity. These are all fire formed, annealed, neck sized and trimmed by the way.
Wouldn't you know it, the weights of the brass directly reflected the volume also. Not a single one was out of line. I could not detect any volume variation what so ever amounts lots but from one lot to the next you bet, 250grainers only filled the 234's to the shoulder. My prerogative... Weight is more important than volume. Volume can be affected by spring back, weight can't. Weight tells you exactly how much material you have.

Bullet casing brass is all made of the same copper/tin composition. It all has the same density. It does not matter what location of the casing has a few more or less atoms of material, because it still takes up the identical volume of the firearms chamber.

Unless someone can show me some data proving me wrong, I do not believe that volume variation amounts same weight brass has any effect at all. If you have weight variation in a lot of identical weight cases, then they are because one has been sized down more than the other. Upon firing all cases big or small, are expanded tightly to the chamber walls. At that moment they have the same capacity, and this is well before complete ignition or bullet movement.

I wish i saved the link for a writeup apparently acompetitive shooter, ballistician ect...
Anyways long n short of it, he took identical weight casings, full lenthg sized some, and only necked some. Obviously the internal volumes were drastically different, yet on target or over the chrono you couldn't tell they werent all identically prepped.
 
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