H 4831 - H4831SC

[RW]

What is the difference loading 4831 to 4831SC I know the difference in that the SC is shorter grains but what is the difference in loading Data?
Thanks,RW

 

[alf]

What is the difference loading 4831 to 4831SC

Zero.

The only difference would be by lot numbers.

 

[bheadboy]

I have tried both in 280ai, 300wm and find their is a difference, however, like Alf, they are so close the lot numbers could be the problem.

never accept that lot changes of the same powder are the same, check them out. with one gun, caliber bullet no other changes, then adjust for the lot change,

on these two versions of the powder, do the same..altering only the normal vs SC. there will be a difference.

Bob

 

[TonyR]

QuickLoad gives exactly the same numbers for both all else being equal except H4831 fills the case better than H4831SC for the same amount of powder. Don't know if that matters for some applications.

 

[Steve Blair]

Tony is right; H4831 SC has about 4% higher bulk density than H4831. This can help if you are using a compressed load. H4831 SC provides a little higher density and less compression. I use SC in .284 Shehane both because of bulk density and kernel size. The smaller kernel size allows lower deviation from the target weight when using a sufficiently sensitive scale.

 

[lloydx2]

With 6.5 284 I still use 4831 Because it has higher load density (fills the case more) Its really whatever your after You want to try and fill the case with out compression or very light compression

 

[Steve Blair]

Just so everyone is on the same page with various densities: [br]
Propellant solid density: The mass density of the propellant itself, usually grams/cubic centimeter. H4831 or SC - 1.55 gm/cm3 [br]
Bulk density: The density to which the kernels pack. This is either a percentage of the propellant solid density or mass/volume that changes depending upon how the powder is loaded. Use of a long drop tube can increase the bulk density as can tapping the charged case or subjecting it to a little vibration. Smokeless powders are usually just under 1 gm/cm3 but some ball powders are a little more. Some flake powders are a lot less. Lower bulk density means less powder in the case per weight, higher bulk density means more. Generally, the lower the bulk density, the more the charge can be compressed. Most small arms use supposes a fixed bulk density that is the powder in a freely poured state with no compaction. [br]
Filling percentage or load ratio: This is a percentage of propellant filling the available space when the bullet is seated. The percentage is dependent upon the bulk density. If the charge exactly fills the available space, it is 100%. Slightly over, it might be 103%. Slightly under, it might be 97%. All three examples could be with the same charge weight, varying by the method used to charge the case and the bulk density achieved. [br]
Load density: This is the load ratio multiplied by the bulk density and expressed in gm/cm3. If the bulk density of H4831 SC is .930 gm/cm3 and 100% load ratio is achieved, the load density of the cartridge is .930 gm/cm3. If the load ratio is 90%, the load density is .837 gm/cm3.

 

[Laurie]

Steve,
a good and very useful set of definitions. Thank you.
Laurie

 

[bozo699]

Steve,
I was completely ignorant to all this, I copied your post and saved it, thank you for a complete explanation and break down of it all
Wayne.

 

[lloydx2]

So higher load density fills the case more and lower load density doesn't

 

[Steve Blair]

So higher load density fills the case more and lower load density doesn't

[br]
Load density is an expression of the average mass contained within the available cartridge space. Generally, higher load density means a higher load ratio but may not. If the case was filled with Unique, it would have a 100% load ratio but a relatively low load density. If the same case had a 75% load ratio with H335, the load density would be higher.

 

[lloydx2]

Thats what I thought

 

[Steve Blair]

In the example of H4831 versus H4831 SC; at the same uncompressed, uncompacted charge weight, they will have the same load density because they have the same propellant density and their bulk densities determine the load ratios. H4831 has a bulk density (in QuickLOAD) of .894. H4831 SC has a bulk density of .930. If 50.0 grains of H4831 fills the case with 100% load ratio, then 50.0 grains of H4831 SC has a load ratio of ~96.2%. Multiplying the bulk density of H4831 by the load ratio produces a load density of .894. Multiplying the bulk density of H4831 SC by the load ratio produces a load density of .89466. This is essentially the same due to rounding errors within QuickLOAD itself.

 

[Erik Cortina]

Just so everyone is on the same page with various densities: [br]
Propellant solid density: The mass density of the propellant itself, usually grams/cubic centimeter. H4831 or SC - 1.55 gm/cm3 [br]
Bulk density: The density to which the kernels pack. This is either a percentage of the propellant solid density or mass/volume that changes depending upon how the powder is loaded. Use of a long drop tube can increase the bulk density as can tapping the charged case or subjecting it to a little vibration. Smokeless powders are usually just under 1 gm/cm3 but some ball powders are a little more. Some flake powders are a lot less. Lower bulk density means less powder in the case per weight, higher bulk density means more. Generally, the lower the bulk density, the more the charge can be compressed. Most small arms use supposes a fixed bulk density that is the powder in a freely poured state with no compaction. [br]
Filling percentage or load ratio: This is a percentage of propellant filling the available space when the bullet is seated. The percentage is dependent upon the bulk density. If the charge exactly fills the available space, it is 100%. Slightly over, it might be 103%. Slightly under, it might be 97%. All three examples could be with the same charge weight, varying by the method used to charge the case and the bulk density achieved. [br]
Load density: This is the load ratio multiplied by the bulk density and expressed in gm/cm3. If the bulk density of H4831 SC is .930 gm/cm3 and 100% load ratio is achieved, the load density of the cartridge is .930 gm/cm3. If the load ratio is 90%, the load density is .837 gm/cm3.

Duh! ;D


Nice explanation Steve, thanks for taking the time to write it up.