weight of shells

[pyrochris732]

i weighed a few of my 5 inch shells and they seem awefully heavy. I am using 1/2 inch pumped stars in these. They average in weight from 550 to off the scale (over 600grms). Does this seem odd to anyone?

 

Ftr I will be lifting these with fg goex since i couldnt quite get my homeade lift dialed in right. Any suggestions with how much to use in relation to the weight? Should i go with the standard 10%?

 

Maybe im just a worry wart, but i put a lot of work into these so i want them to lift nicely.

 

Chris

[Peret]

i weighed a few of my 5 inch shells and they seem awefully heavy. I am using 1/2 inch pumped stars in these. They average in weight from 550 to off the scale (over 600grms). Does this seem odd to anyone?

That seems about right. Remember that the volume of a shell is proportional to the cube of its diameter. So for these sizes (internal diameter, inches) the volume is as given (cubic inches):

 

D - V

1.5 - 1.77

2.5 - 8.2

3.5 - 22.5

4.5 - 47.7

 

Since a 1.75 inch shell (consumer ball) typically has about 30g of comp in it, a 5 inch of similar contents could have 47.7/1.77 times as much, or as much as 800 grams.

 

There are tables published for how much lift to use with larger shells. Generally these are based on 2FA powder, though, which is equivalent to cannon powder, quite a bit larger grained than 1FG. If you put 60-80g of 1FG under your shells you may get more lift than you really wanted. It's probably a bit late for this, but you really should try it with a dummy shell filled with dog food or similar.

Edited June 30, 2010 by Peret

[Mumbles]

Your shells sound about right. I think mine usually come in around 650-700g maybe. I don't remember off hand but you're in the ball park. Normally I use an ounce per pound plus a little, may round up to the nearest half ounce. Your shells are going to fly out of there with 1Fg. 10% might break guns. I remember lifting 6" shells with 1Fg and thought I blew up a gun, it was still well on it's way up after 5 seconds. That was around 100g for 1200g or so. You should be good with around 50-55g of lift if you have no way to weigh the shells. They'll get up there, don't worry.

[pyrochris732]

cool, now i have another question if anyone reads this.

 

I cant find those stupid paper cone cups that everyone uses for lift cups. The only thing i found was wax coated 9 ounce cups. I read somewhere that you shouldnt use these because its tough to attach the cup to the shell. Can I get away with these you think? Every store has their paper cups coated with wax, it drives me crazy.

 

 

[Bonny]

cool, now i have another question if anyone reads this.

 

I cant find those stupid paper cone cups that everyone uses for lift cups. The only thing i found was wax coated 9 ounce cups. I read somewhere that you shouldnt use these because its tough to attach the cup to the shell. Can I get away with these you think? Every store has their paper cups coated with wax, it drives me crazy.

 

Use the wax coated cups if that's all you can find, tape them on and it will be fine. For 5" shells , I personally use coffee cups (7-11, starbucks etc..) just cut them shorter and your good to go.

[Arthur]

Shell weight seems fine, the weight can vary according more to the break carrier, the hole in a rice krispie weighs nothing!

 

Lift cup, cut a circle of brown paper with the radius equal to the shell diameter, then twist this into a two layer cone. and glue it as a cone and glue it onto the ball. Or use a paper coffee cup or a low form paper soup bowl. If the paper is too waxy for glue to stick, rough it a little with abrasive paper.