you can put the 16" barrel on the a1 kit for a colt 605 replica.
i doing one 605 upper out of one of those slickside colts i got of JSE a few years ago. going to use the ess $89 barrel i got from SMG--
i got all "smart ass' and yanked the 20" a1 upper down, flat-toped. scoped and free floated it.
now i got these extra a1 parts just begging to be built--LOL!