New rocket new challenges

Earlier this week saw construction of a new rocket H1 this is a booster of a multi stage rocket it has a spliced pair of 2 litre bottles total capacity 6.4L a larger fin set, a Katz mk3 stager (many thanks air command) 9mm nozzzle , and a60cm main parachute. The sustainer is my daughters rocket K1 this will be used until the new sustainer is built intial tests were promising with no leaks but only one problem we had was the sustainer did not lock into the stager and at 80 psi it jump the gun so next launch we will use a locking tab. I have sanded 1mm off of the gardena connector to make sure the nozzle locks in properly i will update on the next launch day.