pressure difference from lot to lot of retumbo

[wolverine99]

I was using a little retumbo from a friend to see if my gun liked it, and it did so i ordered a keg of it. I know that there are differences in lots but I had to back down from 56.6g of my friends lot of retumbo to 54.5 of my retumbo. Is that a lot or is it normal

 

[loaders_loft]

2 grains? What made you decide to back off? Velocity, pressure signs, group size, etc??

That just doesn't seem right. Check everything - I bet something else is going on...

 

[wolverine99]

that is with all the same primers, seating depth, case lenght haven't change a thing. 55g is still showing ejector button marks. Any thoughts? I am shooting at 1000-1200 feet higher elevation than when I was using my friends powder.

 

[cowboy]

Same scale on both loads??? Something isn't right.

 

[cornstalker]

Was the ambient temperature or ammo temperature significantly different from first attempt to second?

 

[boomtube]

The normal lot to lot variation of cannister powder is usually quite small, your difference IS a bit more than I would expect. Wonder if you chronographed any of the two loads?

 

[loaders_loft]

What chambering and rifle?

 

[highridge1]

I can believe it , I had a newer lot of H1000 that I had to back off 4 grains from a proven load. I am not using H1000 and retumbo anymore ,too much variation. I went back to RL25 which I have used for years in many magnums, and the issues went away.