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Switching from 4F to 3F, do I need to use more?

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Zeus-cat

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I ran out of 4F powder and someone gave me about 3/4 of a pound of 3F. I measure my ejection charges by volume using a Lee Precision powder measuring scoop. Do I need to use more 3F than 4F, or is it close enough to just use the same amount?
 

Steve Shannon

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Although 4f is marginally better, 3f is fine enough for reliable ejection charges. I would not “grind it into smaller particles” because then you really have no idea what you have. One guy I know who tried that ended up with too fine of a mix and he told me it shot his ejection charge cup (an empty cartridge case) right through his av-bay bulk head.
 

shockie

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what's that supposed to mean? Is that some kind of derogatory "shot" at me for being from Kentucky? People have been using mortar and pestels for literally a thousand years to grind up big particles into smaller particles. so FU for your sneering remark.
 

rfjustin

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what's that supposed to mean? Is that some kind of derogatory "shot" at me for being from Kentucky? People have been using mortar and pestels for literally a thousand years to grind up big particles into smaller particles. so FU for your sneering remark.
"so FU for your sneering remark."

Real classy remark slick. If you get triggered that easily, you need to get outside more...
 

dhbarr

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Having thought carelessly about it, I always assumed a longer skinnier chargewell would allow the slightly larger grains to burn more thoroughly before contacting laundry.
 

jimzcatz

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What everybody said... Back in the day Vulcan motors came with 3F. Its fine to use
 

vcp

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Well, this calculator lets you choose between 3f and 4f. It's just theoretical calculations, but it might be good for a relative starting point. You would enter your model's current configuration and 4f quantity, and note the resulting pressure. Then click to select 3f, re-enter that same pressure, and it will give the quantity of 3f to generate that pressure.

The calculator works forward from powder quantity to get pressure, or backward to get quantity from pressure (or work from separation velocity, NC force, et al).

I would be the first to remind everyone that all simulations are wrong, ...but some are useful.
 
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