one of my basses is a cheap indonesian instument (my first bass) it made of good wood & sounds well enough but assembled very poorly with cheap hardware so i want to upgrade this bass first of all: neck bolts screwed directly in the wood, so may i use barrel nuts to fasten a neck? could this measure improve sound? P.S. i`m newbie in repairing
Most bolt on guitars and basses in the world have the screws going straight into the wood. It is a method that has been tested with time and works well. Some luthiers are now using proper bolts with barrels installed in the neck and it does have certain advantages, it certainly makes the neck easier to remove and reassemble cause the threads wont wear out like they can in wood. Some say it sounds better, i havn't tried it yet so i couldnt say about that. I dont think it would be a good idea to attempt this on an already built neck when it has a system that works fine and you say you havnt done many repairs. Also the best inserts i have seen need inserting before the fretboard is attached. In otherwords, not worth the effort or risk of disaster when it might not alter the performance of the bass at all
99 percent of bolt-neck basses on the planet have necks attached as you mentioned. If you have no plans to regularly remove the neck, it's fine. A different fastener is not going to improve sound.