Teach an old dog a new trick.

[mikegaiz]

Please help Teach this old dog a new trick. I have been reloading and shooting for 60 + years and consider my self some what good at it. I was passing on some of my knowledge on when my little grass hopper asked, "Master you said that it is better to have a powder/load that fills the case than one that does not for better accuracy. Then Master, what does it mean when a case is 90% full"? Of course I answered he was not ready to know that fact and moved on. So what does that mean? Is 100 % full mean filled to the case / shoulder junction or the shoulder / neck Junction? I could not explain that. Almost all reloading manuals show % filled capacity numbers for a given powder.
Please HELP Enlighten me.

 

[jds holler]

I may be right or wrong about this, but my definition of "full case" is broad enough to include - from the top of the neck, to a smidge below the base of the neck. I know that's not very scientific, but I don't expect to get excoriated too severely. jd

 

[alb]

If we consider seating depth and bullet geometry, then rather than a particular case junction point, 90% full to me means that I could add 10% more powder without compressing the load.

As an aside, in Litz' recent volume 2, there's a short chapter where this assertion is tested, and the results are interesting with respect to how fill ratios and powder burning speed affect SD.

 

[SheepDog]

The answer depends on how you use comparisons. If you measure your case capacity with water weight then the load density is at 100% when that same weight of powder is used. Will it fill the case? not usually but it is loaded to 100% load density. This is why you will find loads that are 110% load density and higher. If you wanted to know how full the charge of powder was based on the available space in the case and the amount of powder it would take to fill it then you have to start by filling the case with the powder that you intend to use and weigh that charge. Then you can calculate the percent of that maximum volume you use up.

 

[rardoin]

I have always considered it as a percentage of usable capacity; that is, the volume in the case unoccupied by the seated bullet. With this definition 100% 'fill' would mean that there is no space for additional powder in a case with a bullet seated. If I put this charge in a case and seated the bullet 0.050" deeper the charge would be compressed. I have seen 'case fill' interpreted as a percentage to specific locations on the case...like you have mentioned.

 

[Homerange]

Please help Teach this old dog a new trick. I have been reloading and shooting for 60 + years and consider my self some what good at it. I was passing on some of my knowledge on when my little grass hopper asked, "Master you said that it is better to have a powder/load that fills the case than one that does not for better accuracy. Then Master, what does it mean when a case is 90% full"? Of course I answered he was not ready to know that fact and moved on. So what does that mean? Is 100 % full mean filled to the case / shoulder junction or the shoulder / neck Junction? I could not explain that. Almost all reloading manuals show % filled capacity numbers for a given powder.
Please HELP Enlighten me.

As loading manuals generally specify the projectile AND COAL for any given load one can only interpret 100% to mean the power IS NOT compressed with the COAL and projectile combination used.

 

[SheepDog]

The problem that comes with completely filling the available space in a cartridge is that smokeless powder can detonate or snuff the flame out depending on the shape of the kernels. Ball powders suggest the use of magnum powders when less airspace is available for good ignition. The retardant coatings used slow the ignition. With cylindrical and tubular single base powders they tend to ignite easier because the shape of the kernels allow the flame to travel between the kernels easier. When using the charge density ratio there is always room for powder to move during the advancing flame front.

 

[Sniper338]

I consider it usable volume with a bullet seated in place... if you shake the round and hear the powder move around, ita not at 100% full... if you shake it and dont hear anything probably at 100%. When you feel and hear powder crunching wjen seating a bullet, thats over 100%.

This is jmo though..

 

[hogpatrol]

I started reading this until my eyelids started drooping.

https://www.shootingsoftware.com/loadens.htm

 

[TAJ45]

I started reading this until my eyelids started drooping.

https://www.shootingsoftware.com/loadens.htm

So, you would recommend it for a case of the "no sleepums"? ; - ) )

 

[500Stroker]

I have always considered it as a percentage of usable capacity; that is, the volume in the case unoccupied by the seated bullet. With this definition 100% 'fill' would mean that there is no space for additional powder in a case with a bullet seated. If I put this charge in a case and seated the bullet 0.050" deeper the charge would be compressed. I have seen 'case fill' interpreted as a percentage to specific locations on the case...like you have mentioned.

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