How can a 29/40-120 case not fit? That is the motor casing the arreaux is designed for. Don't be afraid of the 29mm reloads. I flew mine last time out on a F52-8T and it was great. It was clearly visible at apogee, no problem with recovery. To be honest, it was bit anticlimactic as I expected a bit more altitude. Next time the weather is good it's getting a G64-10. I think AT's altitude estimates on their motor chart are a bit optimistic. Even on the G64 I expect that the arreaux will stay below 3000'. Should be no problem to track. Fun midpower rocket. For small fields, it flies great, just not very high, on 24mm F39's and F24's.