Lets say someone were to build up one of these to a working G19 variant (say from our friends at 5D Tactical) in Mass. What then? Can you even register it in Mass/do you have to? Federal level says you are good as long as it is for personal use. I know Glocks have been on the AGs hit list for at least 2 seat warmers, does this effect a Polymer 80? If you do have to register, is there a timeframe? 10 days rings a bell.....does it need serialization? Don't think I would build one until things went sideways (maybe next week ), but it got me thinking; what if I had a complete kit laying around 80 Percent Glock 19 Complete Kit | 9mm G19 Kit Online - then what? I haven't changed my view on registering anything, anywhere in today's climate is silly - but can you and how in Mass?