14 August 2003, 23:00
PetePowders of identical volumetric density
I dispense powder by volume and either check weigh every load or every 10th load, depending on intended use.
Looking for a replacement for Reloader 12 (which is no longer available in the UK), I noticed that Reloader 12 and Hodgdon H380 have the same VMD, 0.06910 - I dare say there will be others which match this or other VMDs.
I suspect the answer will be "no" but is this "match" likely to be useful information in any other aspect of performance?
15 August 2003, 01:28
Bob338Volumetric density is only useful to you in dispensing by volume AFTER you know the burn rate. It has absolutely no relation to burn rates which is what affects the pressure. Burn rates are controlled not only by the configuration of the propellant but also by the type and amount of surface treatment on the individual grains. These include stabilizers which affect their burning rate. Propellants with the identical physical construction of the grains can have different surface treatments which change the characteristics significantly even with propellants of identical appearance.
In your case, H380 is a ball powder which is totally different from the extruded RL12. H380 is much slower than RL12. It's much more likely very close to RL15.
[ 08-14-2003, 16:30: Message edited by: Bob338 ]15 August 2003, 02:33
onefunzr2NO!
My reference for RL12 is that the bulk density is the same as water...1.0 gram per cubic centimeter.
It's makeup is 7% nitroglycerin in long tubular granules.
Compare that to bulk density of H380 which is .967 g\cc and nitro content which is proprietary in this ball powder.
My experience is that you work up a load with whatever components you desire using a scale. Then, and only then, do you trust yourself enough to load that specific recipe by volume. Playing fast and loose with volumetric density alone is a disaster waiting to happen. Don't do it.
15 August 2003, 02:42
<eldeguello>NO! H380 is a lot slower than RE 12. On the burning rate chart I just looked at, H380 is #158, and RE 12 is # 139! No real equivalency here at all.
Bob338 is right, RE 15 is just one number away from H380, with RE 21 (obsolete) between them.
[ 08-14-2003, 17:48: Message edited by: eldeguello ]15 August 2003, 03:56
PeteThanks guys.
Eldeguello summed it up nicely with
"NO! H380 is a lot slower than RE 12. On the burning rate chart I just looked at, H380 is #158, and RE 12 is # 139! No real equivalency here at all.
Bob338 is right,"
I really couldn't imagine there being more to it than a simple coincidence of identical densities, but many of you guys will have forgotten more than I'll ever know so it seemed reasonable to ask.
Pete, I heard that Norma N202 is RL-12 ! Made in same factory!Guess where I heard this!!! This is what I wrote down off this forum:N201=RL-7 N202=RL-12, N203=RL-15,N204=RL-19, MRP=RL-22,MRP2=RL-25! N202 is $12.95 a one lb.can at Graf`s !!!!! Ed,