H4350 vs. IMR4350 ???

[ar15barrels]

Alliant powders are greatly effected by tempurature, especially RL-22 in my experience.

In general, powder kernel size will show you the likelihood of pressure/velocity variation due to temperature.
Larger kernels are less temperature sensitive than smaller kernels.
This obviously makes the smaller flake and ball powders more sensitive than the long extruded stick powders.

Here is a great website that will show you photos with a scale of the kernels of many common powders:

http://www.ilrc.ucf.edu/powders/sample_detail.php?powder_id=134

Look at H4350:


And then H414:


Those two powders are very close on the burn rate chart, but VERY different in temperature sensetivity.

[Whiterabbit]

OK you guys have me convinced. I'm gonna qualify IMR for my non-critical applications and save my H for critical ones. That'll stretch my powder even longer.