Legalities
Disclaimer: I am not a lawyer (nor do I play one on any media). I have broken down the laws into something that is more easily understood. If you have any questions (especially concerning Class 3 and interstate sales) please contact the BATF and/or local law enforcement. There are links at the bottom of the page to more sources.
First off for questions on Class 3 stuff (Full-Auto [including sears], Burst triggers, Supressors [silencers]) check the articles on AR-15.com, the BATF, and your local law enforcement. While U.S. law does permit private ownership of full auto weapons and supressors (with appropriate backround checks) some state and local laws prohibit private ownership. Maryland does allow Full-Auto weapons (with a yearly license renewal) and supressors. Most (99.999%) of privately owned AR-15s are semi-automatic only. This means every time you pull the trigger, one round is sent downrange. To fire again you must let the trigger reset (go forward) before you can fire another round.
Q: I thought AR-15s were banned? Well, yes and no. Some states & municipalities have banned them (check your local regulations). Some bans specify by name, some by features, others by commonality of parts. Manufacturers changed names and deleted features to comply with the bans.
Buying & Selling an AR-15 in Maryland: Since this is a site devoted to Maryland shooters I'll let you in the legalities in Maryland. In Mayland most AR-15 style rifles are considered 'regulated' weapons (like handguns). You must pay an extra $10 fee, have seen the safety video (or show a DD-214), and wait the 8 day 'cooling off' period before you can pick up your rifle. You are also limited to one (1) Rifle (or Lower Receiver) in a 30 day period. This also prevents you from buying a handgun during this period, since you are limited to 1 'regulated weapon' per 30 day period (either a handgun or so-called 'assault weapon'). Private transfers of AR-15s are PROHIBITED - they must either go through an FFL (max fee he can charge is $20 per law) or you can go to the local State Police barracks and they can do the transfer. There is an EXCEPTION for Colt Sporter H-BAR Rifle; Eagle Arms EA-15 (probably due to differences with internal parts). These are treated just like any other rifle; private transfers are permitted, there is no waiting period, no limit to how many you can buy at a time, nor will it interfere with your purchase of a handgun. State Police consider any rifle with an HBAR barrel (like the Bushmaster) to be identical. Note: the State Police have indicated HBAR Bushmasters are NOT considered 'regulated' - they are treated like the HBAR Colts. As such you are not required to have a 'safety class' to purchase one. Most dealers don't know this and don't bother to check it out (so expect to pay the fee, wait the time, and take the 'class').
Internet & Out of State Sales Sales over the internet are treated just like any other interstate sale by the BATF. This means that you can not sell directly to another person who resides in another state. You must send the rifle to a FFL dealer in the buyers state who will do the transfer paperwork. The seller may use UPS (or another parcel service) to send the rifle direclty to the FFL (check the BATF website for details). I recommend you verify the person you are sending to is a bonafide FFL before shipping the rifle (contact the BATF) to avoid legal problems. The rules hold if you are purchasing a rifle from another state (it must be sent to your FFL for you to pick up). Federal laws do allow you to cross state lines and purchase a rifle in any state, providing that state does not have laws against sales to non residents (i.e. you could purchase an AR-15 at a gunshow in VA or PA from a dealer). Contrary to media propaganda, all sales from dealers at gunshows require a backgound check (could take up to 3 days, most are instantaneous...If the system is running).
High Capacity Magazines: Maryland passed its own 'ban' in 1996 and only magazines with capacities of 20 rounds or less are allowed to be sold or transferred. The good news is 20 round USGI/Colt magazines are the most reliable, and preferable for prone shooting. If you want 30 round magazines you are going to have to drive to PA, DE, WV, or VA to legally purchase them. There is no law prohibiting ownership, you just can't buy, sell, or take possesion of them within the state.
[Complete Listing of Maryland Laws & Regulations] (Article 27, Section 418E deals with 'Assault Weapons')
[NRA State & Federal Law Review] Click on the 'Firearms Laws' tab (on the lower left margin). Then select the state you are interested in. Also, at the same location is a description of the laws on the interstate transportation of firearms.
[Federal Law - The BATF] Check Federal gun laws and have questions answered. Check out their firearms FAQ.
