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Author Topic: What would be a safe load?  (Read 570 times)

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Offline jeeper1

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What would be a safe load?
« on: July 01, 2007, 01:45:11 PM »
I was able to glum onto a one lb (golf ball size) lead ball that fits perfectly in my GB mortar. The mortar has a one by one inch sub-chamber. I have cannon grade powder as well as 3f. I know 3f is not acceptable (excessive pressure) for a lead ball. So could someone recommend a safe load for the cannon grade powder.
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Offline GGaskill

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Re: What would be a safe load?
« Reply #1 on: July 01, 2007, 02:48:44 PM »
What are your mortar's dimensions?  I have a half scale bronze Coehorn I shoot 2 lb lead sinkers from and use about 220 grains of Fg (600 yards range, too.)  Its wall thickness is slightly over one inch.
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Offline jeeper1

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Re: What would be a safe load?
« Reply #2 on: July 01, 2007, 02:57:22 PM »
4 inch OD. Makes wall thickness 1.5 inches over the sub-chamber and 1.15 over the bore.
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Offline GGaskill

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Re: What would be a safe load?
« Reply #3 on: July 01, 2007, 03:55:17 PM »
I would say filling the chamber with Fg or cannon would be OK.
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Offline Cat Whisperer

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Re: What would be a safe load?
« Reply #4 on: July 01, 2007, 04:01:58 PM »
Quote from: GGaskill on July 01, 2007, 03:55:17 PM
I would say filling the chamber with Fg or cannon would be OK.

OK meaning safe.

Work up to the load if you have the potential of putting the projo out of your safe-to-shoot sector.

Thinking about it, work up to it anyway, that's the safe way.

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Offline jeeper1

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Re: What would be a safe load?
« Reply #5 on: July 01, 2007, 04:38:59 PM »
I've been using 200 grains of cannon grade for golf balls. I was thinking maybe 100 grains of cannon grade for the lead ball. Is that OK.
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Offline Double D

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Re: What would be a safe load?
« Reply #6 on: July 01, 2007, 05:25:56 PM »
Max load for a 1 inch bore (powder chamber is bore in mortar) 195 grains of Cannon.  Remember Switlick says start ridiculiously low.  Also remember that Switlik's chart is for flat trajectory cannons. 

I would start with 25 grains of cannon.  If that isn't enough powder you will know it.  If it is to much powder you will never see tha ball again and won't know if the charge was right.

I used 25 grains for my golf ball mortar to lob the golf balls at the 30 yard stake.  I predict your lead ball will go twice that distance with 25 grains.

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