VV N140 temp sensitivity

[JFrank]

Despite fluctuations in V, did the load still shoot well?
I ask because I'm running N140 as well and have yet to not see it shoot over different temp and humidity swings,
Summer and winter.

Just butting in, you know I didn’t see the radical swings in V vs T and the load shoots pretty decent considering I didn’t test with different primers or bushings rather just looked at one for one against H4895.

 

[Bc'z]

Just butting in, you know I didn’t see the radical swings in V vs T and the load shoots pretty decent considering I didn’t test with different primers or bushings rather just looked at one for one against H4895.

I'd look at bushings for sure

 

[JFrank]

I'd look at bushings for sure

If I were to pursue the load further than yes I would.
When I run out of H4895 I’ll be using N140 and Varget for sure.

 

[jxb]

No manufacturer has this info on their powders. Temp was basically the only parameter changed in my testing, and the velocity fluctuated far more than I expected.
Dave

It's old (2012), but here's some you all might find of interest. Scroll down...

https://hodgdonpowderco.com/wp-content/uploads/2023/04/hodgdon-extreme-series-powders-test-results-for-temperature-sensitivity-1.pdf

for those that don't click on links, go to hodgdon dot com which will redirect you to that site, then resources at the top and choose reference data left side under information. Why they don't put everything including their reloading data page under one site is beyond me and definitely annoying. shop.hodgdon.com has a link at the top to hodgdonreloading.com but I've never found it on hodgdon.com-->hodgdonpowderco.com

Would be super nice if all the manufacturers provided updated/current data for at least their products that are labelled as temp insensitive. There's certainly enough volume sold to justify the time and cost.

 

[JFrank]

What does CUP represent ?

 

[Mulligan]

View attachment 1538956

What does CUP represent ?

If Hodgdon believes that bull squirt, they are dumb enough to drink their own bath water! H4895 is NOT any more “stable” than N -140 or N-135 in my testing.
CW

 

[Mulligan]

View attachment 1538956

What does CUP represent ?

is CUP pressure measurement?


Copper units of pressure or CUP, and the related lead units of pressure or LUP, are terms applied to pressure measurements used in the field of internal ballistics for the estimation of chamber pressures in firearms.


CUP is a special unit of measure defined only for ballistic testing; psi is a standard unit of measure for all pressure testing in the English system. Whether you are testing radiator caps or valves for a nuclear submarine, psi is the same. CUP has no other use


The results of a very quick search……there may be more to the story???
CW

 

[JFrank]

Thanks, I knew id seen that somewhere.

Senior moment I suppose.

 

[JFrank]

If Hodgdon believes that bull squirt, they are dumb enough to drink their own bath water! H4895 is NOT any more “stable” than N -140 or N-135 in my testing.
CW

I seem to recall H4895 going up a bit more than 6 f/s during summer months that didn’t reach 125 F
Moving forward having a decent chronograph now i’ll be able to keep track of these little details a bit easier.

 

[mgunderson]

Shot great is South Africa in 93 to 98 degrees. Yes the speed increases, but it's not stupid peaky on the pressure.

 

[Chilly807]

One variable I've not seen mentioned is a difference in case volume, for example from 308 to a 223.
You might see more difference in a 24 grain 223 load at 0 degrees C vs 30 degrees C, than you would in a 45 grain 308 load under a similar range of conditions.
My recent experience with N140 has been that I had to adjust my 223 load when the temperature dropped over the winter months. The velocity changed enough that it fell out of tune, at least 30-40 fps less than it produced in the summer months.
As with all things 223, it didn't take much to make a difference.
I do know that a small volume case is more sensitive to minor charge weight changes than a larger case, but does that sensitivity include changes in temperature as well?