AR-10: What is a G-3 mag and other questions

[fabsroman]

Just ordered my AR-15 stripped lower today and I'm trying to buy a stripped AR-10 lower. Problem is, everywhere I go I read that there is a difference between Arma-Lite AR-10 lowers and other AR-10 lowers (e.g., DPMS, RRA, Olympic). What is the functional difference between the two types?

Then, I have read about some lowers that accept G-3 mags and others that do not. What is the significance of a G-3 mag, and which ones accept it and which ones do not? Do I really need G-3 mags?

PS - I am going the stripped lower route right now to keep my wife happy. I just spent $6,000+ to build a bicycle, and if I drop another $2,000+ on firearms she will kill me. She hates dipping into savings for purchases other than homes and cars, and I cannot really blame her. However, she gave me the green light on the lowers when she heard what their price was versus the entire gun, and I promised that I would build them up over time. I'll have the bike built for cycling season and at least one of these lowers by fall. Priorities I tell ya.