Author Topic: Blank charge  (Read 808 times)

0 Members and 2 Guests are viewing this topic.

Offline radio2

  • Trade Count: (3)
  • Avid Poster
  • **
  • Posts: 167
  • Gender: Male
Blank charge
« on: June 04, 2007, 07:33:20 PM »
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.

Offline GGaskill

  • Moderator
  • Trade Count: (2)
  • Senior Member
  • *****
  • Posts: 5668
  • Gender: Male
Re: Blank charge
« Reply #1 on: June 04, 2007, 08:42:02 PM »
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.
GG
“If you're not a liberal at 20, you have no heart; if you're not a conservative at 40, you have no brain.”
--Winston Churchill

Offline Rickk

  • GBO Supporter
  • Trade Count: (0)
  • Senior Member
  • *****
  • Posts: 1391
    • http://www.lioby.com
Re: Blank charge
« Reply #2 on: June 05, 2007, 12:38:47 AM »
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?  ::)

Offline longcaribiner

  • Trade Count: (0)
  • Contributor
  • ***
  • Posts: 376
Re: Blank charge
« Reply #3 on: June 05, 2007, 03:06:16 AM »
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.)

Offline radio2

  • Trade Count: (3)
  • Avid Poster
  • **
  • Posts: 167
  • Gender: Male
Re: Blank charge
« Reply #4 on: June 05, 2007, 10:23:20 AM »
Thanks, I like the cardboard idea, I will give that a try.