My suggestion for gluing down the flap was just for a few test motors. I can't imagine doing it for a thousand motors!
I have some cotton swabs on sticks that I use and I "believe" at least one SEMROC kit included one for gluing. If it is successful in preventing a burn-through, at least it is a data point for the tube manufacturer to find a correction (and the old casings becoming collector items...).
Carl, any approximation of the burn-through rate on your test motors? Was it prevalent past a certain delay time? Is a three second delay good and five or more a problem?

Oh, and Bruce is right. B14's!

Chas

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Charles Russell, MSgt,USAF (ret.)
NAR 9790, Lvl 1
SAM "Balls Three"