I know this doesn't answer your question but I have some of the stainless ones with the black followers. A buddy and I bought some and we haven't had any problems with them. I keep reading all of these people saying how their ARs jam and are picky about ammo/mags. I have NEVER experienced any problems with my M4. C-Products makes a good mag and they're Veteran owned.
Cproducts are good mags, and they stand behind them. If you ever have a problem with your mags, contact Larry, and he will make it right.
FWIW, I really, REALLY like their new teflon mags, and they are @ 10 bucks apiece at 44mag.com.
Why curved 20 vs std 20? Edited to add: I see, easier to grab. From my standpoint - curved is not CMP/NRA legal. Have to keep too many different types in inventory.
My hurricane kit includes a 20 in the gun and one (or more) over the shoulder 3 mag pouches w/ 30s. I like the 20 in the gun because it is easier to maneuver in a vehicle. if I am ever in a position where I make it to the mag change, I want all of the rounds I can get.
I shot a two day patrol carbine course with 3 c-products mags that have orange Magpul anti-tilt followers in them. I had zero problems. My c-products are my usual knock-around range mags so I dont have to unload my duty mags which are all all D&H They are great mags
You cannot imagine the number of times that I have looked at pictures of AKs and have said that I "need" one just because, and every time I have one in my hand to purchase I put it down because I can't bring myself to buy it. They look cool, but they have a junky feel to them. I have just not warmed up to them. And no one has to chime in about how dependable they are. I understand.
With respect to mags - C Products are $10, NHMTG are $13 and Brownell's are $17. Brownell's is a current military supplier of mags so these are definitely mil spec. I am going to grab about 10 more which will give me twenty+ (less than 25) 30s and around the same number of 20s. I think I can survive on that since there are millions more out there if push comes to shove. Which of those 3 would you choose?
I purchased a 10 pack of these: http://www.rainierarms.com/?page=shop/detail&product_id=92 from rainier, I've been very impressed with them. as a bonus that black finish looks great. Rainier's service and shipping speed cant be beat as well