[MrMitus]

I'd start small - just 100 cases. Sportsmans Warehouse, Cabelas, Midway, Dillon, CTD all sell popular brass in 100-unit lots. I say start small b/c you may have a good source of range brass and if you get ready to buy in bulk then I'd try the Brassman or similar.
A bag/box of 100 will give you a set known parameters to work from. I'd recommend Win or Rem b/c they are relatively inexpensive for experimenting with. Once you get your technique and load tuned, then you can start big-batch reloading.

@Ike666 - Definitely sounds like a good idea to me. Thank you

It's Federal 223 brass which is heavy with a reduced powder capacity, not Lake City. Lake City is in actuality is pretty good brass and will withstand repeated firings in a AR.

@Tim R - I have heard quite a few negative comments about Federal 223 brass (for reloading)

I'm new here and don't want to start off on the wrong foot.
Anyway... I read this thread top to bottom and was pretty darned impressed with the professionalism, knowledge and courtesy of all posters.
I've been reloading off and on since 1969, when I bought my first RCBS "Junior" press from Gander Mountain. (I was on active duty at the time.) I load .45acp, 9mm, .270, 30-06, 10mm and 7.62/.308. The 30-06 and 7.62 are for my 'collection' of Garands, 1903's and a couple M1A's.
I finally picked-up a 5.56/.223 after years of badgering from my sons, who learned to love that caliber in the Army. Anyway, I bought a Ruger Mini14 "tactical" and hung a Nikon M223 2 to 8 on it.
I started loading 5.56 this past week. Here is the skinny:
Brass - Once fired surplus from Jeff Bartlett (primer pocket swaged by Jeff)
Bullets - Surplus SS109
Primers - CCI type 41
Powder - H335
I carefully resize, deprime and prep all cases. I mic each case (I'm anal!) before priming and give them a visual inspection. Bullets are seated and lightly crimped.
1.74 = Case trim
2.23 = OAL
Here is my results thus far:
Powder charge Ambient temperature Chrony velocity
23.0 72 2,635
23.5 72 2,643
24.0 72 2,706
24.0 55 2,667
24.5 55 2,719
25.0 55 2,773
Fired cases show no signs of excessive pressure.
Since the Mini14 has a 16.12" barrel, I would expect that I'd see somewhere around 2,850 in a 20" AR15.
Anyway... Do my results square up with the experience of other readers? I'm leaning toward making this my go-to load.
Thanks in advance

@Wyo Dutch - I haven't had a chance to start loading 556 yet, but I'll definitely be saving your results for possible future reference. Thanks and welcome to the site You might find that you'll get some pretty detailed responses if you start a fresh thread since this one has been open for a while.

1.751 is fine. You could probably get away with 1.755. If your close to 1.760, trim. Personally, I trim anytime its over 1.755. Anything under I don't bother to trim.

By the way I use only winchester or LC brass for accurate and high quality reloaded rounds. I use whatever I can get...WCC, PPU, Rem R&P (dont know what that is) for plinking.

@brokenanew - What do you do with cases that are already shorter than 1.750? Trash?

Just a "for what it's worth": I always size new brass, just as if it were fired. measure and trim new brass also, if needed. just saying.

@FM12 - Thanks for your input. I'll definitely be sure to go through the same steps

Great information in this thread, thanks for everyone who took the time to reply.

Great reading.

@p loader - I agree, everyone has been such a huge help. I didn't imagine I would get this much input in such a short period of time.