Delayed Three Inch Display Shell

[displayfireworks1]

This is a video clip from my next video. Has anyone experienced these delays when you light a display shell. It almost makes you think it is going to blow apart in the mortar. These delays cause choreography problems.
I hear different theories on why this happens. Please feel free to post what you know about this. This shell is a three inch Sunny Brand display shell.

http://www.youtube.com/watch?v=dXGb9iMHbXI

[Pyro Nation]

I have never had that happen yet... "knock on wood" ..do you know who made the shell?

[PyroManiacs]

Yes Dave, We have had that happen in a show we did on July 4th, but they were 4" chains doing it.

[hatsgoods]

I had a few on my first hand lit show do that

[displayfireworks1]

Here is a copy and paste comment from my YouTube channel. The nice thing about having these videos on YouTube is you can get input from all over the world. This may explain why there is delay.
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2012/2013 ish shells from certain factories can have this delay. They switched to using a metal band similar to a staple to bind the baggie of lift around the quickmatch. This band binds the joint so hard it delays the pass through of fire. When visiting our factories this year, we asked that they be tied instead of using this metal band but they assured us they now have it resolved. We took random shells from production and shot about 3 dozen with no delays. They said it was a change in blackmatch formula. I would assume it's Perc match as the appearance is a little gray when compared to the BP match.

[SCPyrotechnician]

Sunny is not the only shell that does this. Lidu shells also do this.