I have had a SBB for 7 years or so thats had many flights and as far as fins go I'd suggest the following:
1. sand tube well where fins will be glued on whether you use the gusset things or not. no shiny "glassine" coating should remain.. get down to the paper... so sand first, draw alignment lines next over the sanded sections..
2. Never have tried the pin hole rivet thing but sounds like a good idea. however, I've never really had a fin pop if you use a decent epoxy fillet and follow step 1.
3. MOST important and wish I did this: After removing fins from balsa sheet, apply a thin layer of a good wood glue to each side using a paint brush or whatever and laminate it with regular paper... some suggest really thin tissue paper or notebook paper, but I really like the thicker inkjet printer kind of paper... makes the fins at LEAST 3 times stronger, maybe more. You really need it for a long lived SBB since those fins are so big and swept back so far. of course do this before attaching the gussets and use something flat and heavy to hold everything flat or things might wrinkle or warp. also be sure not to use too much glue because when you squeeze the fins to let dry, excess will squirt out the sides and possibly make the fin's root bumpy with glue making it really hard to sand...
4. tack in place with thin ca and when satisfied with alignment do the epoxy fillets (since you can adjust a little if you use very small amounts of ca by applying to one side only and if fin is tilted to one side, apply pressure in opposite direction and ca other side.. works great... or make an alignment tool...)
5. finally I continue with the wonders of epoxy: apply a thin coating of epoxy to the trailing edge of each fin and even around inside the body tube (for recessed motors) to protect from heat. a thin layer is all you need and its well worth the minimal weight.
Other tips:
1. forget using 20 sheets of wadding and try a nomex sheet. Works wonderfully; I've never had chute damage when using a properly sized sheet of nomex on any rocket... (had some deployment failures from using a sheet way too big, but that's another story... basically bt60 rocket, estes c6 wont push out a sheet intended for 2.6 inch tubes!)
2. Build the engine mount so that the little metal tab of the motor retainer clip inside the rocket does not block RMS casings. (i.e. clip the tab part that goes through the motor tube to half its size so that it doesn't protrude into the tube past the depth of the motor block, if used... and I'd recommend you do use a block unless you plan to use a funky long 24mm motor. If you mod for an Estes E9 you can just build the mount normally because the RMS delay part of the casing will fit right inside an adapter spacer used with D12 motors and not be affected by the metal tab.) D12s and even E9s are plain boring after you try F24s or F39s! even E11/F12s are really cool.
3. ummm, thats it i guess... hope this helps... oh, use nylon chutes, an 18" should do fine if you're not at a high altitude at ground level.
4. ok thats it, i think im babbling now
