Powder Volume

[castnblast]

Have any of you noticed a difference in the volume of powder from one lot to the next? I ask because I noticed a difference in the "amount" of powder in my 22-250. Here's the deal. I "0" my scale every time I go to reload. I powder trickle each shot to the EXACT weight. I check, and recheck. In my last batch, I noticed there was little "extra" room in the case. Same powder, IMR 4064, same bullet, Sierra Game King 55 gr. spitzer boat-tails, same COL, and same measured 36.50 gr. of powder. Oh, and yes, same brass. ONLY difference...Opened new can of powder. I pulled one of the "tighter" rounds and remeasured. 36.5 to the T.

I'm stumped
AND should this be an issue to concern myself with? I have always R-L'd for belted mags, so I never noticed a difference before.

[brselman]

I would guess that the only real question is, "Do they shoot differently?" Otherwise, it is just an incidentaloma!!

[amamnn]

As long as you are dropping powder uniformly from one session to the next, then you might want to check density.

According to usually reliable sources, powder manufacturers set the standard for density of powder a long time ago, settling on an allowed variance of 16% This means that the powder can be 16% less dense or 16% more dense than the can you bought that was right on, or the can you started with was 16% light and the next was 16% heavy. This is why it is important to measure the density of every can or bottle of powder you use, and label it, if you are loading for accuracy. This does not mean that powders WILL vary that much, it is only the maximum allowed, by mutual consent of the powder makers. Winchester at one time claimed a max variance of +/- 2.5% Powder manufacturers catering to match shooters will have tighter tolerances, as well. Also remember that temperature and humidity will affect density, so the old "load in winter shoot it in winter....etc." saw has validity.

Lee has a formula posted in their technical help section that deals with density and the use of their dippers or bushings, in the case of shotgun loading. You do not really need to know the exact density of the powder, since your really interested in keeping things consistent from loading to loading, so you need to be able to compare the new can of powder to the old one that worked so well for you in the past. BTW, the Lee dippers are labeld in cubic centimeters.

You can determine the density of the powder as compared to the standard, which is water at room temperature. The number assigned to water density is "1" All you need do is divide the weight of the powder by its volume.
D = W / V
So 2.2 cubic centimeters of powder that weighs 1.9 grams has a density of 86.4% of water. You slap the label on the can and when you buy the next one you measure it and adjust your load accordingly. I know--it's metric---but---it's really quite easy these days with digital scales that weigh in grains and grams; you just need to be sure you're using the grams setting for this.

[castnblast]

Thanks. I thought I had recalled that. I bought the previous can at an old gun store, and it had dust on it when I got it. No telling how old it was. The new can came in the plastic container, so there is probably some serious age & obviously lot differences between the two. What is your thought on buying 8 lb bottles? For this round, it is "the" powder. I'm going to experiment with different bullets of the same weight for different purposes and see how it performs. If they all perform well (I'm sure the charge will need to vary a bit) then I'm thinking I'll go that route. 1 lb of powder yields approx. 190 rounds (191.78 to be exact) the latter to allow for spills etc. I figure at that rate, It should last about 2-3 years for that gun. Is that too long to store powder?

[ZeroJunk]

I just finished off a keg of IMR4350 that could be 30 years old.I bought a new 1 pound can and loading 58 grains in a 30/06 the new powder came almost halfway up the neck.The old powder was just at the bottom of the neck.I changed from SPBT to Nosler Partition and they shot about an inch higher and an inch to the left.Not much difference for hunting purposes,and I don't know whether it's the powder or bullet change that caused the difference.

[amamnn]

Zero, mysteries like that are why we only change one thing at a time, usually.

Back to the original subject. Powder stored properly can last a lot longer than your planned use. I would still check denisty.

[ZeroJunk]

AMAMNN,I happened to run out of IMR4350 when I needed to load some hunting rounds.I would bet you it is the bullet and not the powder.The charge weight is the same.No sign of pressure change.Group size is satisfactory.These are hunting loads for a 30/06 and although the old powder may have been a few percent more dense,it's just a curiosity for me as opposed to a benchrest shooter.

[castnblast]

1+ on bullet. Changing bullets will just about always (key, just about, not always...confused yet?) change your POI.

[Bill T]

"I just finished off a keg of IMR4350 that could be 30 years old.I bought a new 1 pound can and loading 58 grains in a 30/06 the new powder came almost halfway up the neck."

I did the same thing with some older DuPont IMR 4831 with my .300 Weatherby. When I opened the new can of IMR brand 4831 it went halfway up the neck as well. I had to drop the charge by almost 5.0 full grains. Even if I hadn't caught it I would have been fine since I don't run things to the ragged edge. It pays to always check every time you open a new can. Bill T.

[castnblast]

That stuff is really course. Try tapping the case, and sifting it before loading. It seems to cut down on that. I shoot a max load out of my 22-250, and I found it pours better after sifting. Not sure why, but it does.