Well, I have owned just about every type of semiautomatic weapon under the sun, and in the end, I always come back to the AR platform.  It's what I trained on, and first learned marksmanship on, it is a terrific and highly modifiable system.  But hey - I am preaching to the choir here.

I intend to purchase one complete rifle, one lower, and two uppers in the coming weeks.  Here is my plan to have as many bases covered as possible.  Feel free to critique me or offer advice.

1) Colt AR15 M4A3 LEO carbine, courtesy of SteyrAug.  This one will of course be 5.56mm, with a few CQB options.  I have  a good Eagle 3 point sling, KAC foregrip, and Bushnell Holosight awaiting it right now, though I may alter my setup eventually.  I don't know which handguards to go with yet (most likely KAC), or whether or not to add a light.

2) High quality A2 lower - either Colt, Bushy, or RRA (feel free to chime in here).  This one will get a custom trigger, though I don't know much about trigger jobs yet, so I will shop around before sending it off anywhere.

3)  6.5 Grendel upper.  These of course aren't cheap, but I have a reloading setup at home, so I think I will be able to manage it soon.  High quality glass, a Harris bipod and an upcoming three-day scoped rifle course will net me a quality long distance weapon, with the training to use it.

4) .22lr upper.  If I am not mistaken, Bushmaster makes one of these, with no attached flashhider or muzzle brake, which is good, because I intend to purchase a suppressor for this one.  Add an Eotech optic, and (hopefully) some full capacity magazines, and I will be ready to go.  This upper will be for my M4 lower.  I have quite a bit of the Aguila .22lr SSS saved up for just this setup.  Hopefully I will achieve solid accuracy at 100 yards.  That is all I really want out of this upper.  

Well, I still have a few things to figure out on this one, but that about covers it.  Short, medium and long range accuracy, plinking, suppressed shots, and CQB all covered.  I like to accomplish as much as possible with as few tools as I am able.  I can always buy any number of other custom uppers, or accessories to add to these setups.

Now, feel free to give me the scoop on what I really need, guys.

I know 5.56 is the millitery designation. However isnt the difference between the two so small you can fire 223 or 5.56 or vise versa in each chamber

If I am not mistaken, rounds designated 5.56mm fire at a higher FPS than .223 rounds, although the external measurements are the same.  Rifles chambered in 5.56mm can tolerate higher pressures than .223 chambers.

Undoubtably someone will be along shortly to smack me down with a more accurate explanation.

what exactly are you two trying to figure out about 5.56mm???

5.56mm and .223 caliber are actually different in dimensions, but ever so slightly.  It works the same as with .357 magnums and .38s.  You can fire a .38 out of a 357 magnum, but not a 357 magnum out of a .38.  you can't (read SHOULDNT) try to fire a 5.56mm round out of a chamber made specifically for .223 and marked as such.

As far as a dedicated .22 you can save a few bucks by just getting a conversion kit for your AR.As far as lowers the ones you mentioned are all great quality except colt has larger fire control pin holes and is expensive,Bushmaster standard parts but expensive,RRA standard parts and 60 to $70 cheaper but tighter than I like,AMEETEC arms has a fit like bushmaster without the price and all the quality.

I already have my BM lower and vltor CAR stock and  LMT 14.5" M4 upper w/ RAS II and aimpoint M2 ready for the ceremonial joing of the receivers on sunday nite


I also will be ordering a Colt 6520 AR-15A2 gov't carbine either directly thru colt or from Steyr AUG