I 2nd Rob on this. Rm2 is pretty unbeatable. It's reasonably priced and don't even bother worrying about the brass, there's no way the brass cap will get hot enough to ever be an issue. There's enough space and airflow to take care of that. It would take some pretty extreme heat to be an issue and I've never had an atty get so hot I couldn't touch it. If you can touch it, it ain't that hot. Certainly not hot enough to cause some ridiculous problem with fumes or whatever people are afraid of happening. Your not taking a lighter or torch to it.
Anyway... We've all been rocking rm2's for quite a while and no lockjaw or whatever yet.