by Fyodor » 11 Jul 2014 01:10
It is supposed to make the pressure more uniform. Actually I'm not convinced that a higher uniform pressure is better than a lower less constant pressure. Powder under high pressure does tend to bridging or ratholing, both are very undesireable and will cause less controllable, less uniform loads. In the extreme you might end up loading 200 rounds and then wonder why the hopper is still full...
To get a uniform low pressure, which is best to keep powders flowing from a large reservoir through a small hole, I suggest using powder baffles or "powder roofs" as we call them in Germany. This will create an even more uniform pressure, because it's completely independent from the actual level in the hopper, it will prevend bridging and ratholing and has sucessfully been used for decades.
I would not use an extra weight on top of the powder. Only exception would be a powder level checker, but these tend to be as lightweight as possible, too.
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