Manufacturing a Title II device (includes silencers, etc.,) requires a manufacturers tax stamp, and BATF approval of the operation. A manufacturer can make devices for experimentation and for sale to authorized purchasers. But unless you have the stamp, making a machinegun in your basement is illegal, whether you ever transfer it or not. "Manufacturing" a firearm includes making it out of something, whether that something is a semi-auto firearm or a barbeque grill. No, talking about making machineguns is not a conspiracy unless there is evidence of intent to carry out an illegal act. Talking about robbing a bank is not illegal; drawing floor plans, maps, renting a hideout and buying guns would bring the talk into the realm of a criminal conspiracy. If you ever need a technical question from ATF, they will answer over the phone (and not use caller ID). Unfortunately, like the IRS at tax time, an agent's word is not official. If a question is important, write them and get a revenue ruling, which is binding throughout the US and on all agents. Needless to say, don't begin with "I've done this is it legal?" By the way, A US district court ruling is only binding in that district.
[This message has been edited by Jim Keenan (edited March 18, 1999).]