I think with a cartridge that is efficient as 6BR, it isn't about what burns barrels faster... because it's not hard on barrels anyway. Though its more about what stays in a node longer. Powders with slower burn characteristics, when combined with heavy per cal bullets, typically will provide a more gentle pressure curve and will subsequently produce a wider node.
Remainder of post not directed at @Joel Danielson, but rather for general informational purposes.
A byproduct of this more elongated and more gentle pressure spike, is its typically easier on the barrel. More barrel life is never a bad thing, after all. As a result, I typically will run the slowest powder I can get away with. This typically provides the best case fill and the most consistent performance across the widest range of conditions and round count. I'd rather
lightly crunch kernels than have free space in that case. If you can combine that with a 40 degree shoulder angle and a long barrel, you can really see some extremely wide nodes. In an attempt to quantify this by some measure, you can go from having a node that's 1 grain wide, to having a node thats 1.5-2.5 grains wide.
As with all things ballistics, there's a piece to this equation that hasn't been talked about much: The barrel. The right answer from a component selection standpoint is
always going to be driven by first hand experience with the specific barrel/rifle system you are working with. Threads like these serve as a guide only. Someone else's ability to tune their rifle will not make your rifle shoot better. The bulk of my work is done on Benchmark barrels which are produced by TS Customs. Despite the fact that I've received positive feedback from many customers that have tested my component recommendations on their various brands of barrels/rifles... there is still the ever present variable of what your individual barrel will like. Your brand might not play well with common component choices. In order for you to know,
you must do. There is no shortcut. There is no trick. There is no advice that can be substituted. Some barrels will simply not respond well to commonly held recipes. Subsequently, if you really want to get your rifle shooting, you can not assume the .38 MOA performance offered by the "internet golden load" to be the best it can shoot unless you've done adequate testing to ensure no further advances can be made. You may have your preferences regarding bullet selection or powder choice, but the rifle/barrel needs to be listened to.
You may also be short on time and the common internet golden load might shoot well enough for your liking and you'll just run with it.
There are no wrong answers which meet your requirements. If you're happy with how something is performing, then you're happy. However, unless you've done the work you won't know... Unless you've done it on dozens of rifles in that same chambering, you won't have a wider understanding of the cartridge.
!! Only sport I follow.
