Gentlemen:
Google “powder burn rate” and you’ll find numerous sources ranking smokeless powders according to the speed at which they burn. Pretty much every powder from every maker can be found.
Following are several Alliant products listed in order from fastest (Red Dot) to slowest (Blue Dot).
Red Dot
Green Dot
Unique
Herco
Blue Dot
Since there’s obviously some confusion about uses and/or terminology, maybe it best to ask, “What applications are best for fast powders and, when are slow powders better?” The simple rule of thumb is that faster powders are designed for lighter loads. Slower burning powders are formulated for heavier loads.
However, light and heavy are relative terms. So how do we distinguish one from the other? One factor is speed. We would all probably agree that if other variables are equal, a 1300 feet per second (fps) load is “heavier” than an 1145 fps load.
The other big factor is weight of the payload (shot charge) compared to the diameter of the chamber and bore. For example, a one ounce load in 12 ga. is generally considered light while a one ounce load in a 20 ga. is considered heavy.
Hunting loads provide additional examples. Every bullet maker sells ounce and an eighth 12 ga. hunting loads. Several make ounce and an eighth 20 ga. loads. It normally takes a three inch 20 ga. hull to do it. The obvious reason is there is less chamber and bore space in a 20 ga. The additional space required for an ounce and an eighth shot charge in the 20 ga. is created by using a longer hull.
Assuming we now have a general agreement on light versus heavy, a look at Alliant’s Reloader’s Guide is in order. The section for 2 ¾ inch 12 ga. hulls has recipes for shot charges ranging from three quarters of an ounce to an ounce and a half. Notice as the weight of the payload increases, the burn speed of the recommended powder decreases. This inverse relationship holds for all loads in all gauges.
Perhaps THE underlying issue of this entire subject is chamber pressure. Faster burning powders behind heavy payloads can create pressure spikes exceeding SAAMI standards. That is why there are no Red Dot loads listed for 12 ga. recipes with 1 ¼ oz. (or greater) payloads or in ANY 20, 28, or .410 loads.
On the other end, the slow burning powders including Blue Dot, have very slow burn rates which generate chamber pressure very slowly. That’s why magnum powders are particularly poor choices for recipes with light payloads. They simply don’t create the required pressures for complete powder burn and proper performance. They aren’t dangerous; they’re just inconsistent and perform poorly behind light payloads.
Using Red Dot and Blue Dot as the extremes of burn speed, notice there is overlap in applications. Every powder has a RANGE of applications where it will give acceptable results. It’s the overlapping areas we’re really debating. Green Dot overlaps with Red Dot on the light end and Unique on the heavy end. Herco overlaps with Unique and Blue Dot and so on.
Green Dot burns fast enough to provide acceptable results in some one ounce 12 ga. loads. That’s why Alliant publishes a few one ounce Green Dot recipes. However, Green Dot is specifically formulated for and performs even better in heavier loads. That’s why there is a PLETHORA of published loads for Green Dot in loads with heavier payloads. That’s also why Alliant describes the PRIMARY use of Green Dot as handicap trap loads.
In deference to Messrs. Waalke, Shooting Jack, and Birdogs, neither Mr. Ireland nor I said Green Dot won’t work in a one ounce load. We didn’t describe it as awful, dangerous or something to be avoided at all costs. The experience of Mssrs. Waalke, Shooting Jack, and Birdogs notwithstanding, the OPTIMAL use for Green Dot is loads heavier than one ounce.
With respect to those with contrary opinions, pretty much everything I’ve stated above is “reloading 101”. It aint rocket science and it most definately isn’t anecdotal.
It isn't factual because it is my opinion. Rather, it’s my opinion because these are established concepts based on tested data from industry professionals. A primary source is SAMMI and its member companies. Those members include ATK (corporate parent of Alliant) and Hodgdon Powder Co. among others.
Respectfully yours,
sissy