Load Tables, Burn Rates & powder selection

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lineofsight

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How are tables constructed? Is no constant - not weight, not velocity, not pressure.... so how compare? Why not use same pressure so can compare velocity at same pressure or load density...

For example:
H4895 is faster than Varget, uses less powder and produces less pressure at starting load. So... how compare at same velocity and pressure?

H4895 is faster than IMR 4895, uses about same or less powder, produces less pressure and more velocity... seems contradictory however pressure of H measured in CUP and IMR in PSI (manufacturer's table...).

Benchmark is faster than H4895 & IMR 4895 uses less powder, produces less pressure and lowest velocity... well that makes sense, so how compare to H/IMR 4895...

So... how do you use tables & burn rate to select powder?
Burn rate can see useful in short barrel/light bullet or long barrel heavy/bullet
Table can see charge weight & case capacity.

Any more useful than that (other than starting loads)?
 
"...How are tables constructed?..." They're averages of the loads tested on that particular day. Some loads are tested with an actual rifle, some with a 'Universal' receiver. That and environmental conditions on the test day can produce varying results.
Burn rate charts only tell you that a powder burns faster or slower than anther. IMR4895 and H4895 are virtually identical. One is higher than the other because it's a list. Like Ben says, the burn rate isn't a consideration when working up a load. Follow your manual religiously.
 
Well, you can use them to get ideas for a powder that may perform similarily and then look for load data. Useful in some ways, but not overly.
 
Am comfortable with a couple different ways of building up a load, just trying to figure out if there is useful information in the tables that am not seeing or whether all they do is provided suggested min. & max.

Was hoping to be able to compare load density, speed & pressure for powder selection but not seem geared to that.
 
Not really... only real value to my mind is to suggest powders that you may want to experiment with if you're looking for relatively faster or slower powders.
 
The burn rates of powders are only approximates.

There are a lot of factors that make up the burn rate and how the powders react. For example, burn rate is affected if the powder is a single base, double base, type of coatings, shape of powder granule, density of powder granule, additives, etc.

Stick with published loads.
 
Is it worth considering burn rates when thinking about barrel wear?
I know one has to work up loads based on published data but does a slower burning powder generally cause less wear and tear?
 
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