That's what I thought. If it does not have a detachable box mag, it is not an assault rifle, PERIOD, according to ATF regulations, therefore can have all the features exept grenade launcher, which is a DD as someone stated before. Actually I am going to try to make a receiver similar to the FAB 10 from a regular AR15 stripped lower. All they did was weld shut the magwell and rivet a 10 round mag in place, and add $200 to the price. Surely I can do that in my workshop. It's just such a shame to castrate a perfectly good receiver like that, it makes me cringe (I don't live in Kalifornia) and my friends say they won't go to the range with me anymore if I do it but....to have all those features I miss so much...I don't know, might be worth the pain. Opinions on a Kalifornia receiver when not living in Kalifornia (to have all features, legally)? Would anyone else do this, or have I gone mad.....