A few notes... Registered Receiver (RR) vs Registered Kit (RK) – Both have their pros and cons. Registered receiver guns can have any broken part replaced with the exception of the receiver, which would need to be repaired by a competent machinist/welder. The RR does have some risk of cracking, although I think it would take blatant abuse to break a USGI receiver. Registered kits offer the most as far as mobility but if a substandard part was registered (for example, an aftermarket trip lever), you may have trouble getting it to run or fixing it if it should break. As long as a RR is in good shape, I wouldn't hesitate to buy one. Same for the RK, if the registered part of the kit is of good quality, you should be good to go. I ultimately went with a Registered Receiver and have no regrets. Magazines – I have had good luck with the Korean 15 rounders – no experience with the Korean 30s. USGI 15 rounders are the most reliable in my experience. “J” marked 30 rounders (USGI contract) and Taiwanese 30 rounders (from J&G Sales) are of excellent quality, although both seem to be slightly less reliable than the typical USGI 15 round magazine. Buy as many magazines as you can. Ammunition – Aguila, Prvi Partizan, and Federal run great in my RIA/Inland M2. Armscor 30 Carbine runs okay but I do encounter more problems with it than with the other brands - it fails to cycle the action much more frequently than the other three. I have also encountered Armscor rounds that “collapse” when they are chambered. I do have a small supply of Lake City ammunition but I keep it for collectability purposes. Parts – Parts are available but may be expensive. Be wary of having all seven parts as that constitutes a machine gun in the eyes of BATFE. Avoid having a duplicate of a registered part (for example, don't have a spare disconnector lever if you have a registered disconnector lever). I think the most likely parts to wear out and/or lose would be the disconnector spring or plunger, the nine spring, or the disconnector lever. Summary – Overall, I really like the M2 Carbine. It's light, accurate, controllable, and offers a high rate of fire. Sometimes, it suffers reliability problems on full auto but overall it's a great gun for a reasonable price. Ammunition is somewhat more costly than other calibers but not too bad. In my opinion, the M2 Carbine is a fine piece of American engineering with an interesting history and a decent combat record.