dramatically increase the accuracy of burst fire, but the system never truly worked, and was later dropped. The grenade launcher portion of the design proved much more interesting, however, and work continued on that portion. The Springfield entry was most interesting for its layout. It used two 30-round magazines in tandem in a bullpup layout, taking rounds from the front magazine first. However, their massive magazine-fed grenade launcher pushed the weight to , and it seemed unlikely this could be reduced by much. AAI's design was the least technically advanced. The flechette gun portion was somewhat heavy, but fired at 2400 rpm. Their grenade launcher was a simple single-shot weapon; their semi-automatic version was not ready in time for testing. The conclusion of the testing was that none of the weapons were ready for development into a combat system. The AAI flechette portion and the Winchester grenade launcher were both interesting for general development, however. More worrying was the result of general testing of the flechette concept. While the weapons delivered on their promise of extremely high rates of fire and excellent penetration, the rounds themselves were extremely expensive to produce, and the darts could be easily deflected in flight even by heavy rain. Finally, the rounds gave off extremely loud reports and had a huge muzzle flash, making the guns easily visible in low light. A second round of testing followed, with the Springfield model adopting the Winchester grenade launcher with a disposable magazine and a new side-by-side layout for the flechette magazines. AAI's design was equipped with their semi-automatic launcher, which was now complete, and a new plastic buttstock/sighting system. Neither updated version proved very reliable and both were over the limit. In 1966 SPIW was put into "maintenance mode" and the M16 adopted. AAI continued development at a low level, and eventually managed to dramatically improve the reliability of their XM19. However, this revealed another problem: heat buildup in the chamber was great enough to result in "cook off". Changes in the Army command structure and the adoption of the M16 made interest in the SPIW fade, and eventually the project was allowed to die. AAI's original "simple" grenade launcher turned out to be a major success: it was selected as the M203 in 1968 and became a common weapon under the M16. The Future Rifle Program In 1969, the Army started the Future Rifle Program, and