just wondering what is the difference you have experienced in powder lots from one to the next with your standard loads
powder fps variation from batch to batch
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Re: powder fps variation from batch to batch
I've seen lot to lot vary by hardly any to over 120 fps variation. When you switch lots, you need to test the fps again. I have not had any issue with the group size changing, just the fps, which was surprising. I switched lots of H4350 in my 260 and picked up an extra 80 fps. It was nice, but I'd be upset if it was the other way around. Varget has also been one to change.
I've seen lot to lot vary by hardly any to over 120 fps variation. When you switch lots, you need to test the fps again. I have not had any issue with the group size changing, just the fps, which was surprising. I switched lots of H4350 in my 260 and picked up an extra 80 fps. It was nice, but I'd be upset if it was the other way around. Varget has also been one to change.
Re: powder fps variation from batch to batch
A new batch of powder is equivalent to changing the bullet or the case. Start low and work your way back up. And to decrease the number of time you have to do this, buy several juggs at the same time.
A new batch of powder is equivalent to changing the bullet or the case. Start low and work your way back up. And to decrease the number of time you have to do this, buy several juggs at the same time.
Re: powder fps variation from batch to batch
HOLY CRAP!!! 120 fps is crazy. i usually buy powder with the same batch# for a specific caliber to last the life of the barrel. varget and h4350 are my two main powders.
HOLY CRAP!!! 120 fps is crazy. i usually buy powder with the same batch# for a specific caliber to last the life of the barrel. varget and h4350 are my two main powders.
Re: powder fps variation from batch to batch
If the new powder usually is the faster of the two (and especially if it's by 120 fps), what's happening is your old powder is absorbing humidity and the individual granules are gaining water weight. The granules don't swell but they do gain weight, which means a given weight charge in the new powder will contain less water and more powder than the powder in the bottom of the old bottle did.
I had two bottles of RL-19, same lot#, bought on the same day, stored side by side. Six months later, I was near the bottom of the first bottle so I decided to compare what was left to what was in the still unopened bottle. I found the old powder had gained a full 9% of its weight in water. After five days with a pack of desiccant, MVs from the two were equal to within the SD of my load.
This is why I always open a new bottle and add a packet of silica gel desiccant and let it rest a week before I start load development. It supposedly is better that the powder has just a touch of moisture in it but I don't know how to control it so there's just a touch. But I do know how to get it to near nil, and keep it there. So I know the bottom of the bottle will shoot nearly the same as the top did.
If the new powder usually is the faster of the two (and especially if it's by 120 fps), what's happening is your old powder is absorbing humidity and the individual granules are gaining water weight. The granules don't swell but they do gain weight, which means a given weight charge in the new powder will contain less water and more powder than the powder in the bottom of the old bottle did.
I had two bottles of RL-19, same lot#, bought on the same day, stored side by side. Six months later, I was near the bottom of the first bottle so I decided to compare what was left to what was in the still unopened bottle. I found the old powder had gained a full 9% of its weight in water. After five days with a pack of desiccant, MVs from the two were equal to within the SD of my load.
This is why I always open a new bottle and add a packet of silica gel desiccant and let it rest a week before I start load development. It supposedly is better that the powder has just a touch of moisture in it but I don't know how to control it so there's just a touch. But I do know how to get it to near nil, and keep it there. So I know the bottom of the bottle will shoot nearly the same as the top did.
Re: powder fps variation from batch to batch
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Fred_C_Dobbs</div><div class="ubbcode-body">If the new powder usually is the faster of the two (and especially if it's by 120 fps), what's happening is your old powder is absorbing humidity and the individual granules are gaining water weight. The granules don't swell but they do gain weight, which means a given weight charge in the new powder will contain less water and more powder than the powder in the bottom of the old bottle did.</div></div>
One time when I changed jugs of Varget, I got some hot loads. Then after a few uses of the powder from the new jug, it went back to where it used to be. I opened the jug in Feb when it was humid. The first set of reloads were hot, the next not so much, and so on. The jug (8 pounder) was sealed all the time except for when pouring powder into the thrower and when pouring the triffling of remaining powder from the thrower back into the jug.
Your explanation is the first one I have heard that correlated my humidity observations and jug-to-jug pressure changes that "go away" over time.
Thanks, and good observation!
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Fred_C_Dobbs</div><div class="ubbcode-body">If the new powder usually is the faster of the two (and especially if it's by 120 fps), what's happening is your old powder is absorbing humidity and the individual granules are gaining water weight. The granules don't swell but they do gain weight, which means a given weight charge in the new powder will contain less water and more powder than the powder in the bottom of the old bottle did.</div></div>
One time when I changed jugs of Varget, I got some hot loads. Then after a few uses of the powder from the new jug, it went back to where it used to be. I opened the jug in Feb when it was humid. The first set of reloads were hot, the next not so much, and so on. The jug (8 pounder) was sealed all the time except for when pouring powder into the thrower and when pouring the triffling of remaining powder from the thrower back into the jug.
Your explanation is the first one I have heard that correlated my humidity observations and jug-to-jug pressure changes that "go away" over time.
Thanks, and good observation!
Re: powder fps variation from batch to batch
Using Varget to develop a load for my 20" Savage 10FP .308, I had good velocity at 2640fps at 43gr, 168gr SMKs, fed brass, CCI200s......Fast forward 2 years, same brass and primers, it now takes 45.5gr to get the same velocity. I lost 100fps between lots of powder.
Using Varget to develop a load for my 20" Savage 10FP .308, I had good velocity at 2640fps at 43gr, 168gr SMKs, fed brass, CCI200s......Fast forward 2 years, same brass and primers, it now takes 45.5gr to get the same velocity. I lost 100fps between lots of powder.
Re: powder fps variation from batch to batch
+1 on the dessicant packs. Humidity definitely impacts energy/gr.
I just got into a new jug of Varget. The new and old 8 pounders are different lot numbers, but hit the same fps.
+1 on the dessicant packs. Humidity definitely impacts energy/gr.
I just got into a new jug of Varget. The new and old 8 pounders are different lot numbers, but hit the same fps.
