3-6-9 shot bursts

dont use burst or full auto use double taps they are mor efficient... go out and get some SAS (Special Air Service) or other combat manuals to see how to best use your guns... but ultimatly it depends on situation, it is true that a burst of more than 3 rounds is a waste,  only use full auto if your providing cover fire. but bursts in paintball are almost useless because if they are short they usually go in one general area, and in long bursts you might as well use full auto in which you either cant aim or are providing cover fire. Burst mode is used by the military to ensure a kill, in fact the SAS used "double taps" for hostige situations until it was found that some people still could muster the strength to shoot back so now they shoot untill the target drops. but in paintball double taps are still usefull because it allows you one shot to range, then another shot to kill. and you are in full control, so if you arnt hitting your target you are not wasting 6 rounds on a piece of ply wood

Darur, did you just turn british?

9 round burst...pphht, why?

Mechanically speaking, it should be feasible. The 3rd burst has been a feature on M16 rifles for a long time, and safe-semi-burst-full is a common trigger group for MP5s, which posess a small trigger frame. Real firearms have no more space in the trigger housing than a paintball marker, so the mechanism should fit if someone figures it out. I can't find mechanism schematics, unfortunately, however the concept of a trigger, sear, adn bolt is the same- ther'es very little differnec ebetween the trigger mechanism in my assault rifle and that of a Tippmann, except for a slightly more complicated sear which would be optional in a paintball marker anyway.

The trouble is that a paintball marker cycles far faster than an M16 rifle- the bolt has much less distance to travel, and so the cycles per minute are much faster. Because of this, and becuae a bullet is much more resistant to crushing and impact than a paintball, the big limitation is the loader. Unfortunate,y if you slow down the cycles per second, you slow down the speed of the bullet, which throws the valve out of whack. Theoretically with longer bolt travel, a lighter valve spring, and a low pressure system, you could make a mechanical fully auto that wouldn't blend paint, as long as your leader could keep up- a Qlaoder for instance. Aside from that, the only mechanical alternatives are the ATS markers where the mag is mechanically linked to the firing sequence, and the RAP markers where each one's in a cartridge to protect it from squashing. A select-fire mechanical mag fed paintball marker is one fo teh hoyl grails of MilSim. ATS ahs done it with good success, but slimmer packages are always in demand. Scepter has something in the works, and probably a few other companies as well. Keep your eyes and ears open in the next few eyars- something good is bound to be in development somehwere.