Burn Percentage

[Ned Ludd]

Webster - the fact that you're still trying to argue about this doesn't mean you're right. It just means you're stubborn and/or ignorant. Optimizing loads is all about optimizing combustion. If you don't get that, or refuse to get that, or simply don't want to be wrong, this discussion is complete waste of time. Otherwise, taking some time to better understand what optimal burn rates and optimal combustion conditions have in common might be beneficial for you.

 

[dcali]

Look at the 308 charts on this website. They are using Varget with light and heavy bullets. I am not saying Varget is the best choice.
http://www.accurateshooter.com/cartridge-guides/308win/

If the powder is to slow because of below 90% burn why are they getting good velocity? If 10-15% of the powder is burning outside the barrel wouldn't you get low velocity? I believe real world results before computer generated data. Don't believe everything a computer spits out. Chrono the velocity.

My Sierra manual list these powders with the higher velocity with their 110 gr bullet:
H322 3300 fps
748 3200 fps
H335 3300 fps

The Berger manual list 10 powders for their 115 gr bullet. All above 3114 fps.
Some of the highest fps listed:
H322 3206 fps
H335 3161 fps
Ramshot Tac 3195 fps
Win 748 3241 fps
BL-C-2 3234 fps.
N135 is listed for the 125 GR bullet.

The manuals are conservative. I always assumed that the listed powders that give the highest fps for a given bullet weight are the most efficient for whatever reason. Compare these powders to others close in burn rate.

It looks like the Berger manual is based on software calculations, not test firings. They don't really say one way or another, but there are a few hints in the book that lead you to believe it's all just QuickLOAD. There is no mention of test setup, no mention of equipment used, and there is a brief note about software. Before their book came out, if you asked them for load data, they would send you a QuickLOAD printout. Anyone know if they actually test their data?

 

[waldo1979]

I've been working these 116gr bullets for a while. My last batch had blow-by issues where the necks didn't seal. This was with Varget. Carbon got every where but was mostly contained in the bolt face and extractor groove of the brass.

I think the 10% unburned powder just means there is suboptimal combustion. It's like a carborator running a bit rich but just enough to not cause a problem.

I also ran into ignition issues with this load (Palma brass) and have switched to a slightly warmer primer.

I'm getting closer.