Lift charge for four inch shells

[cogbarry]

Hi all,

I was hoping someone would have an idea where I can start with the lift charge required for 4 inch ball shells. I've used my home made BP for 3 inch shells but more often used commercial 2fg "Goex FFg". I granulated my own BP to approximately the same grain size and if anything, it was hotter than the commercial ffg. In any case, I'm quite sure this is too hot for four inch shells. The quick answer I'm looking for is the correct commercial BP (non blasting grade?) to use. I'll try my own stuff once I am comfortable that it is well tested. Most tables out there (such as on passfire) list the charge recommended with 2FA but I can't easily purchase this. I'm wondering if Fg or the cannon grade stuff would work for 4 inch shells. Thanks in advance for any help.

[Algenco]

Hi all,

I was hoping someone would have an idea where I can start with the lift charge required for 4 inch ball shells. I've used my home made BP for 3 inch shells but more often used commercial 2fg "Goex FFg". I granulated my own BP to approximately the same grain size and if anything, it was hotter than the commercial ffg. In any case, I'm quite sure this is too hot for four inch shells. The quick answer I'm looking for is the correct commercial BP (non blasting grade?) to use. I'll try my own stuff once I am comfortable that it is well tested. Most tables out there (such as on passfire) list the charge recommended with 2FA but I can't easily purchase this. I'm wondering if Fg or the cannon grade stuff would work for 4 inch shells. Thanks in advance for any help.

 

 

it isn't "too hot", after you go above 6" larger grain is needed.

I use 8% of shell weight with Paulownia BP

 

try 10%

[cogbarry]

it isn't "too hot", after you go abovePaulownia 6" larger grain is needed.

I use 8% of shell weight with Paulownia BP

 

try 10%

 

You mean the FFg is not too hot? I use about 10% of shell weight for 3's. Usually ends up between 18 - 28 grams as I recall. I've seen some pretty hard lifts though. I know ball shells can take a lot but I don't want a flower pot or a burst gun. I'm also trying to avoid any low breaks.

 

The only home made BP i've made is with skylighters hardwood charcoal (OK, I guess) and the pine stuff I made with white pine 2X4's (better). Don't have any Paulownia handy, not sure if I could get my hands on this or not. In any case, I prefer to take the all unnecessary unknowns out when starting something new so I'd like to start with commercial BP 'til I've got this shell size down. I'm thinking my meal coated rice hulls will work well to burst these shells and I can lose the booster.

 

Thanks for your advice.

[Xtreme Pyro]

For 4" shells your homemade BP will do just fine. Like Algenco said, start with 10% and if that's too much back it down to 8%. For my 4" shells I use Balsa BP granulated through a spaghetti strainer and use 8% of the shells weight since I found 10% to be too much. Good luck! Edited August 23, 2011 by Xtreme Pyro

[Mumbles]

XP, do you mean 8%? 1/8th the shell weight is more than 10%, 12.5% to be precise.

 

If you're intent on using 2fg, Blesser and a few other sources in Best of AFN II tend to recommend something in the vicinity of 1oz. I've seen a few varying between 0.9 (25g) and 1.1oz (31g). This is pretty close to the 1oz per lb. that fulcanelli recommends, though that is in reference to canister shells. I trust that 1oz of 2Fg will get it up to a safe height. Perhaps start with 35g if you want to play it safe. 1Fg will also work. I've used it up to 6" ball shells. I used it in the same amount I'd typically use 2FA, and those shells really got up there. Lancaster has a note in Best of AFN II that when using 4FA about 75% of his normal amount of lift such as those listed in his book was about right. 4FA is pretty much equivalent to 1Fg.

[Xtreme Pyro]

XP, do you mean 8%? 1/8th the shell weight is more than 10%, 12.5% to be precise.

 

Yea I did, I forgot to change it. Sorry for any confusion.

 

 

 

[dan999ification]

dummy fire time, you wont regret it if you take precautions, you may be suprised that all is well.

i know how it feels to question your bp but once you test its all over unless you encounter problems.

8%

10%

12% if its really bad

if your bp will burst it should lift

 

dan.

 

 

[cogbarry]

Thanks everyone! I tested my BP with baseballs in a 3 inch gun and got 11.5 seconds of air time with 20 grams. Lost the baseballs in the woods but heard them land. My concern was that my BP or FFg would be too hot and damage the shell and/or gun. From all the responses above, it seems I don't need to worry about this until 6 inch or more.

[dan999ification]

Thanks everyone! I tested my BP with baseballs in a 3 inch gun and got 11.5 seconds of air time with 20 grams. Lost the baseballs in the woods but heard them land. My concern was that my BP or FFg would be too hot and damage the shell and/or gun. From all the responses above, it seems I don't need to worry about this until 6 inch or more.

 

 

i think smaller shells 3" and under can have more strength as they have less surface area for the forces to act on, though i dont go bigger.

also why they tend to have stronger break charges than their large friends, this is by no means going to make up for poor construction,

if in doubt top fuse them and use a suitable gun.

theres nothing like the feeling when it goes up and stays up

 

dan.

[cogbarry]

With the 3 inch shells I basically hot glued both sides of the time fuse right to the shell on the bottom. I was planning to use a fuse washer for the 4's along with something for a passfire. Hopefully, this will help stiffen/strengthen the bottom of the shell and prevent lift gas leaks into the shell. The gun will be your standard HDPE 4 inch mortar.