I want to get a fair amount of the same ammo for the 5.56. I want something that will be affordable in quantities of 500-2000. I want a round that will not be detrimental to the barrel overt the long term and one that will be accurate. FMJs are the cheapest, but I gather they are not great for the barrel and lack in the accuracy department. Green tips? Brands? 55 or 62 grain preferable. Thanks for any input.
I am guessing from your questions you want brass cased stuff? FMJ can be very accurate, but you get what you pay for. People must be thinking of the FMJ's with a mild steel jacket and copper wash when they talk about increased barrel wear. What is the twist rate on the barrel you are going to be using it from? Honestly buy some single boxes of different brands and weights and see what your gun likes the most. Good excuse to do some shooting. I just did that with a new gun. Bought some cheap plinking stuff and a few single boxes of better stuff to see what the gun likes. Same shipping.
Don't discount foreign ammo. Wolf Gold is not made in Russia, it is made in Asia, Taiwan I believe. I recently bought some Yugo Privi Partisan in .308 and it looks and shoots a better than the bulk Lake City I have. PMC can shoot well.
Freedom munitions. Large variety, and good pricing. As for the1/9 twist it favors the lighter weight bullet.
I have lots of wolf steel cased stuff. It works to 200 yards for varmints. Over that I hand load. Pmc bronze shoots good. I've bought 1k round case of it.
Buy a few boxes of differ types and have a range session to see what your rifle likes. Fmj won't hurt your barrel at all! Green tips are the least accurate bullet on the planet. Wolf gold, is good stuff, and can be found on sale for around $300 per case (1k)
Here's some info on twist rate and bullet weight. http://www.gunsandammo.com/ammo/pair-barrel-twist-rates-ammo/ 1/9 is sort of middle of the road. Like other's have suggested, but several packs of ammo and find out which one gives you the accuracy you want, and then start buying more!