I know Estes made a B8-3 for Centuri at one point, but not sure why the B14-3 never existed.
If blow-thru was a problem it would seem it would be even worse with the B14-0 and we all know that one worked for years.
The B14-6 has always had me scratching my head though...makes NO sense unless it was specific for some competition event that made the B14-6 optimum, but I have no idea what kind of event that would be.

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When in doubt, WHACK the GAS and DITCH the brake !!!

Yes, there is such a thing as NORMAL, if you have to ask what is "NORMAL" , you probably aren't !
Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY.
ALL systems are GO for MAYHEM, CHAOS, TURMOIL, FIASCOS, and HAVOC !