There is no 'factory' class. There is Open and Target Rifle (TR), period. Use a factory rifle, or a full-blown custom, it doesn't matter.
Last year SOA/Fullbore, 1st & 3rd F/TR were Savage 12 F/TRs - essentially stock (one had been bedded). 2007 FCNC, 2nd & 3rd F/TR were Savage 12 F/TRs. 2008 SOA, only two F/TR shooters showed up. One took 15th out of 27 overall - Open & TR, all calibers. 2008 FCNC, 3rd F/TR was one of the brandy new Savage 12 Palma rifles.
Five out of ten of the USA F/TR team going to England next year are shooting Savage rifles... four of them factory rifles (caveat - those shooters are also members of Savage's F/TR team).
Could the other companies like Remington, Winchester (whoever owns them this month), etc. make good platforms for competitive rifles? Sure. Both Winchester and Remington used to do just that years ago. For whatever reason they both abandoned the people who wanted a nice factory match gun, and Savage seems to be stepping up to the plate. A Savage target action with target accutrigger, recoil lug, and barrel nut is in the low $400 range. A person can get a ready made rig from the factory, or shoulder a bit more of the responsibility and build one to suit given the time and inclination. Neither way is more 'right', in my opinion.
Monte
Team Savage
Team USA F/TR