I think the law requires that the lock go into the chamber like the Omega locks (basically the only lock that's approved). Not totally sure on that though. I have still been made to buy a lock, even when the gun I bought came with the cable-type or trigger guard locks.
Honestly, I don't feel like getting into an argument with someone because I mentioned their favorite gun shop and all they're doing is "covering their asses" so it's ok. I personally know where I will and won't shop anymore and that's about the best I can do. If you're not sure about the shop you're doing the transfer at, call and ask if it's ok to supply your own MD-approved lock.
