4 inch mortars exact dimensions

[johnybmb]

Hello everyone!

I'm quite a beginner with display shells, so far the biggest commercial shells I fired were 3 inch, and I'm trying to move on to 4 inch shells but I got a question and maybe you could help me out: How much should the ID of the mortar be in order to fit a 4 in shell? This might sound like a stupid question, but my problem is that I only have access to 96.8 mm ID HDPE pipe (110 mm OD, with a 6.6 mm wall thickness). I'm wondering if a 4 in shell would fit my size of mortar, because usually the shells are not exactly 4 inches in diameter, but somewhat smaller (at least with my 3 inch shells, the difference is about 4 mm between the shell diameter and the mortar ID, which is 76 mm). For the moment I do not have a commercial 4 in shell to test it out on my mortar, and I would not like to buy a bunch of shells and later discover that I don't have a mortar to fire them out of. I also do not have access to commercial 4 in mortars, as I'm only an amateur pyro, and in my country it is illegal to buy mortars without a licence. So far, I have only fired homemade shells out of the same mortars, and I made those to fit the mortar diameter exactly, but with commercial shells, the mortar has to fit the shell...
So, could you help me out on this one? Maybe some of you have access to 4 in shells, and you could measure them for me?

Thanks in advance!

[VikingPyrotechnics]

Why don´t you buy a GFK Mortar?? If you can get some class 4 firework, you also can get a mortar?! :D
It´s pretty cheap also. And safer any ways....

The ID varries between 100 and 104mm on my mortars ...
Greets
VP

[johnybmb]

I can't buy a commercial mortar. I can get the shells from some friends that work for a fireworks company, but no mortars... The HDPE that I have is very strong, at 6.6 mm wall thickness, and I got it for free...
Anyway, thanks for info, though it seems like 100 - 104 mm is larger than my mortars; don't know if the 4 in shells would fit in the mortars that I have. Maybe I'll take a sample of the pipe that I have, and ask my friends at the fireworks company to try and see if the shell fits the pipe. If it fits without the need for pushing the shell down the mortar, then it is all okay. Although that way there would be almost no space between the shell and the mortar walls, which would lift the shell to greater heights than initially intended; and that is not always a good thing, with greater height the apparent burst size is smaller...

[Pyro-T]

To avoid some misunderstanding: the size named on the shell is not the shell's size. It's the ID the mortar must have.

[johnybmb]

I am aware of that, and that's why I asked if anyone might have access to a 4 in shell and measure it's diameter to see if it is under 96 mm, and in that case I think I could use the mortars that I have without problems.

[johnybmb]

I finally solved the mistery. I actually got two 4" shells and tested them with my mortar: they fit perfectly; well, actually they are a little bit of a tight fit, i.e. the shell, together with the quickmatch, fits exactly in the tube without free space on the sides; but not as tight as to require pushing it down the tube. The shell easily glides down the tube, and it is also easily taken out of the tube. I will have to actually fire one from the tubes that I have, to see how higher it goes compared to commercial mortars (unfortunately it will have to be estimated, since I don't have access to commercial fiberglass standard tubes). I hope the difference in altitude won't be that high so as to ruin the effect's visibility.

So, I guess the actual size of a 4 inch shell is approx. 95 mm in diameter, and together with the quickmatch leader is goes to around 96 mm. Well, I have only tested one brand of shells (Jorge 4" T1504 - Peachblow to Chrysantemum (http://www.jorge.com.pl/eng/fajerwerki-profesjonalne-film-25-1404-2.html)) but as I will get other shells, I will post the results.