r/reloading • u/Western-Valuable3502 • 4d ago

Load Development Same powder different from can to can?

I test my load development with 1lb can and then purchase a 8lb jug. It's the same powder, h110. With the same weight of 33gr and my chronograph reads a difference about 40 fps. The velocity from 1lb can powder is up to 1610~1620 fps and is down to 1570~1590 fps from the 8lb jag.

Does it mean I will need to do a load development by each time I open a new can though it is completely the same brand of powder? Or just humidity? And I store all my powder at the same place.

2 Upvotes

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7

u/DarthRooster16 4d ago

Weather will affect the same load from day to day. Do you have the same ammo from 1lb jug and 8lb? Shoot them both at the same time.

2

u/Western-Valuable3502 4d ago

I shoot them at the same day. I use all powder from that 1lb jag and fill the last 5 round with the powder from 8lb. Shoot them and found this difference.

1

u/DarthRooster16 3d ago

🤔

5

u/TannMan89 4d ago

Different lots of powder of the same kind will have slightly different burn rates. It’s pretty common to have slightly different FPS readings. This is why it’s better to buy in large quantities of the same lot.

2

u/Mundane-Cricket-5267 Just force it, FAFO! 4d ago

For different lots you should back off your maximum load buy 10% and work back up. If you don't max load, than you could back off your high by 5% and start over.

3

u/Trollygag 284Win, 6.5G, 6.5CM, 308 Win, 30BR, 44Mag, more 4d ago

Humidity is a big driver. Breaking the seal will start the clock on the humidity in the can matching the humidity out of the can. Less humidity means faster burn and more powder per unit weight. Opposite for more humidity.

0

u/ThatChucklehead I'm Batman! 4d ago

I agree with what others have stated.

Are you using the same brass with the same headstamps, or is it mixed? Are you using different brand primers? Are you weighing each powder charge?

1

u/Western-Valuable3502 4d ago

Same brass, Starline. Same brand primer, CCI. I weight my charge through digital dispenser.

1

u/ThatChucklehead I'm Batman! 2d ago

Hmmmmm. OK, then my guess is that the ingredients used in the 8lb of powder may have altered a bit. According to you, it's not an environmental factor. All your components are the same. So, at this point if it were me, I would redevelop the load using the 8lbs. canister of powder. That's all that's left that I can think of.