Relative burn rate chart that includes Somchem, Vihtavuori and Lovex powders?
Hi, all.
I have reached a point of "analysis paralysis"!
I have a collection of propellants, viz. Somchem S335, Somchem S341 (Riflex Blue), Somchem S355, Lovex S062, Vihtavuori N150 and Vihtavuori N550.
I can't find two charts on the internet that agree with each other on the relative burn rates of these powders and, a separate query to Google's Gemini gives me a completely different answer too!
From comparing multiple sources, my own rating of these powders, by burn rate (fast to slow) is:
Somchem S335
Somchem S341 (same for Riflex Blue)
Lovex S062
Somchem S355
Vihtavuori N150
Vihtavuori N550
Can anyone please confirm this, or provide a corrected order?
The reason I want to set my record straight is just to know which powder I should be using for which loads. My (perhaps naive) understanding is that a faster burning powder is typically better for lighter bullets travelling at a higher velocity and slower burning powders better for heavier bullets - regardless of calibre.
As an example of my frustration - I've been trying to develop a load for my .375 H&H, using Sus-tac 221gr bullets and Lovex S062 powder, but am simply unable to settle on a load that produces relatively consistent speeds and GOOD GROUPING. I came to my own conclusion that the Lovex S062 powder is perhaps just too slow in its burn rate for such a light, fast bullet out of a .375 H&H. I've now opted to use Somchem S335 instead, as that seems to be a more versatile, and faster burning powder. I recently loaded Impala 200gr bullets with the Somchem S335 for my .375 and it has worked like a charm!
Any assistance would be much appreciated!
Des
Oh wow - this is a topic that can be discussed endlessly and there is no wight or wrong ... the burn characteristics of a powder are determined by a number of factors:
explosive heat (energy conversion potential )
burn rate and function (functions are never linear - some start fast and then slow down ...) , which depends on the chemical composition and shape of the powder
density and bulk density (if bulk density is high, you can fit more powder into the case, which converts to higher pressure and energy)
Some burn rate charts might take only one variable (i.e. initial burn rate) . Others take a weighted average (of explosive heat, initial burn rate, etc.) , some take empiric values of similar characteristics (i.e. weight of the charge for certain calibers). This leads to a different ranking and can be confusing.
This statement, "My (perhaps naive) understanding is that a faster burning powder is typically better for lighter bullets travelling at a higher velocity and slower burning powders better for heavier bullets - regardless of calibre," is not correct. The rule of thumb is that smaller calibers (smaller case capacities) made for shorter barrels use faster powder. The powder should fully convert before the bullet leaves the barrel. Otherwise, a too-low powder conversion creates massive muzzle flashes and noise. So typically, pistol and revolver calibers use fast-burning powders as well as military calibers (for economic reasons, they often have small brass and short barrels like .223 or .308).
The load tables on xxl - other than on other sources - also show the powder burn, fill rate, etc. This helps a lot to find a suitable substitute for anyones default powder that might not be available. It also often lists the recommended powders. Hope this clarifies and helps.