Quote Originally Posted by darkker View Post
So despite Hodgdon's marketing machine cranking out....Questionable information, simply being a ball powder doesn't tell you anything about sensitivity; it's about tech date.
We have done lots of temp testing and "cook-off" testing with the Pressure Trace system in the Creedmoor. Remember there isn't a powder that is just universally insensitive, it is ALWAYS about application. In the Creed, RL-17 is easily every bit as stable as H4350, if not more so; same can be said of Superformance. The deal with RL-17 & Supr is how they burn, and can confuse you if you only rely on "Signs", or watch velocity as a linear trend line. H4350 when used within it's happy pressure range burns very linearly, as do most powders you know of. RL-17 is somewhat progressive burning powder, meaning that the burning curve changes with pressure being run; and Supr is VERY progressive. I don't have my Photobucket log-in on me to post pics, but to try and give you a mental visual between the two types:

Regular powders ignite and immediately spike to max pressure, then very quickly drop-off. Any burning speed powder does this, the only change is in the total pressure being run.
Progressive burning powders spike up but then plateau off, so think of a mesa or a butte. Because they don't spike and drop immediately, they change burning speed and can "push" with high sustained pressure for much longer than a non-progressive powder.

The progressives aren't just a linear deal like the classic powders, so how much of a plateau Vs. peak there is can really change depending upon the operating pressure. I've posted these graphs before, but in the Creed I can drop 10,000 psi but only lose 50-ish fps from max velocity when using Superformance. The trouble is if you can't see the burning curve, meaning only watching velocity or staring at brass as some absolute pressure indicator. Remember the 10% lot variation warnings, they are VERY real; I've pressure tested a few things that had more than 10% difference between lots. Extruded powder has it's burning rates controlled by geometry(volume) and ball powder is by coatings.

As far as powders, with the lighter bullets URP is very stable.
i'm a little new around here and I would like to read up on the studies that have been done that you refer to, and I really like graphs too, so could you please give me a link to some of this reading?

thanks,
Richard