Blank charge

[radio2]

Hi all, I have a steel soda can mortar and want to know how much powder to use to make a good report without a projectile? And what do I use for a wad?  I shoot 350 grains of FF and a soda can full of cement for a max charge, But don't know about how much BP to use for a blank charge.

[GGaskill]

That sounds like about a max blank charge to me already.  Try cutting a bore sized disc of corrugated cardboard and pressing it down to the bottom of the bore for a wad.

[Rickk]

You can cut cardboard disks with a holesaw in a drillpress if you remove the pilot drill and resharpen the edge with a grider so that it is a razor sharp taper, removing the teeth in the process. If the teeth are still there it will grab and tear.

If you soak the cardboard in baking soda saturated water and then let it dry, you won't light your wife's garden on fire (did I say that? 

[longcaribiner]

A suitable "report" is as much a function of the wads used as the powder.  As I understand the physics of the process, (and I may be wrong) you need a sufficiently heavy wad to cause pressure in the burning powder, and sufficient powder so the wad approaches or exceeds the sound barrier.    In my 1.25 inch diameter cannon, I found that two 1/4 inch thick leather wads made a really great boom with only 130 grains of powder.    The wads are cut with a old fashioned leather punch and fit very tightly.  That half inch of leather has suffiicient weight.  Any less powder doesn't move the wads fast enough, or create enough pressure behind the wads.  Lighter wads don't seem to work.   

(Once July fourth, I  accidentally took a branch out of a neighbor's tree with some wads.)

[radio2]

Thanks, I like the cardboard idea, I will give that a try.