H1000 temp (in)stability?

[SDHNTR]

I’m getting some strange results with H1000. Seeing about an average difference of 25-30 fps over 10-12 shot strings with a differce in temp of about 18 degrees.

Shot a couple weeks ago and it was pushing 80 out. Shot this am and it was cool and cloudy, about 60 degrees. Average velocity was measurably less. Same everything wrt components and load. I know no powder is truly insensitive to temperature, but this change seems like a lot, given a fairly minor change in temp. Anyone else seen this?

 

[wind gypsy]

I’m getting some strange results with H1000. Seeing about an average difference of 25-30 fps over 10-12 shot strings with a differce in temp of about 18 degrees.

Shot a couple weeks ago and it was pushing 80 out. Shot this am and it was cool and cloudy, about 60 degrees. Average velocity was measurably less. Same everything wrt components and load. I know no powder is truly insensitive to temperature, but this change seems like a lot, given a fairly minor change in temp. Anyone else seen this?

Cases baking in the sun when 80 vs cloud cover @ 60 by chance?

I've not seen that kind of swing directly from ambient temp over a bunch of cartridges with H1000.

 

[SDHNTR]

Cases baking in the sun when 80 vs cloud cover @ 60 by chance?

I've not seen that kind of swing directly from ambient temp over a bunch of cartridges with H1000.

No, of course not. Nothing like baking in the sun or cooking in a hot chamber. I’m very mindful of the things I can control.

I’m stumped. It’s the same lot of powder, same lot of once fired brass, same scale, same everything. The only thing different was hot and dry weather compared to cool, cloudy and misty weather. I didn’t think temp or humidity would make that noticeable of a change.

 

[Aviator]

Are you running a max load? I’ve noticed with a max load of H1000 or any supposedly temp stable powder I see a slight jump in velocity as the temperature gets in the 80’s especially if your in the sun or as the chamber heats up.

I hardly ever shoot when it’s that hot most of the time I’m shooting when it’s cold out and that’s when I see the most stability from say 60 degrees down to 0..

 

[gelton]

IME I have noticed about a .5 reduction in velocity for every 1 degree of temp change with H1000, nothing compared to what you mentioned, but temp swings definitely matter.

 

[SDHNTR]

Are you running a max load? I’ve noticed with a max load of H1000 or any supposedly temp stable powder I see a slight jump in velocity as the temperature gets in the 80’s especially if your in the sun or as the chamber heats up.

I hardly ever shoot when it’s that hot most of the time I’m shooting when it’s cold out and that’s when I see the most stability from say 60 degrees down to 0..

Yes, I generally do too. Come to think of it, that’s probably the warmest I have done a shooting session. The load is near max, but not really pushing it. I would have to go about .8 grains more to see any signs of pressure.

 

[SDHNTR]

IME I have noticed about a .5 reduction in velocity for every 1 degree of temp change with H1000, nothing compared to what you mentioned, but temp swings definitely matter.

I would love to see a chart of sorts that maps out temperatures stability. So it sounds like the slope of the curve of sensitivity is not lineal? Results are more consistent on the cooler end of the spectrum? Is this just your anecdotal experience or has this been proven somewhere?

 

[gelton]

I would love to see a chart of sorts that maps out temperatures stability. So it sounds like the slope of the curve of sensitivity is not lineal? Results are more consistent on the cooler end of the spectrum? Is this just your anecdotal experience or has this been proven somewhere?

Personally tested and observed.

 

[gelton]

I would love to see a chart of sorts that maps out temperatures stability. So it sounds like the slope of the curve of sensitivity is not lineal? Results are more consistent on the cooler end of the spectrum? Is this just your anecdotal experience or has this been proven somewhere?

Also - I think Quick Load has the charts you are looking for.

 

[sierracharlie338]

I’ve run h1000 in a few rifles now and have not see anything that big in that small of a window. Curious if you find a cause of it.

 

[A382DWDZQ]

Might be worth a call to hodgdon and give them your lot# and/or maybe try a different lot of H1000.

 

[SDHNTR]

Now that I think about this, I wonder if the difference lies in the Labradar, and not the load at all. Anyone had issues with low reads on Labradar in misty/foggy weather?

 

[Harvey_NW]

Do you use graphite lube? Possibly bullet weld?

 

[SDHNTR]

I do use graphite and these loads were only a few days old.