I have six 223/5.56 rifles, four are AR's (a pair of 24" Stag 6 Super Varminters, and a pair of 16" uppers that swap onto the Stag lowers) and, two are bolt (A 20" MVP Predator, and 24" Savage 11VT) rifles. All have nominally NATO chambers. My 223 700 VLS was my only SAAMI chamber, but that has been passed down to the next generation.
Trying to keep brass and loads segregated per barrel would simply make me bananas. Instead I try to go the other way and make up generic 16" barrel and 24" barrel loads. I have the 20" covered with Fed Fusion MSR 62gr factory ammo; it's a very good match, and I have plenty of satisfaction with the way the 16" barrels shoot that as well. All my rifles except the Savage shoot from AR magazines, and my OAL seldom gets altered from the initial arbitrary mag length minus .010" spec. For the same reason, I measure my COAL at the Projectile Tip instead of at the Ogive.
For the 24" barrels I have a 50gr Nosler BT load, and am reworking my 600yd 75gr HDY HPBT-Match load downward from 24.4gr of Varget to the 23.5gr-23.7gr area. I use the Hornady Match bullet because one of the rifles (the 24" Savage) has a 1:9" twist and the Hornady works well in all the three 24" barrels. The 50gr Nosler load is an absolute screamer, but still holds up fine in the 24" 1:8" Stag barrels.
All of my brass is resized on the same f/l die, with the same generic adjustment (to fit the SAAMI Spec case gauge I have). There are no function issues, and accuracy is very acceptable in each of the rifles. I haven't shot the 75's in the shorter 16" or 20" barrels, but am working up a generic load for them using the Sierra 65gr GameKing; it will be quite near the hotter end of the Hodgdon load guide (63gr data) spectrum. For the most part, the 16" guns are intended for M193 and M855 Mil-Spec ammo.
Are the loads optimal for each barrel? No, but they don't need to be; what accuracy the generic loads provide is certainly good enough to settle for, and the reduction in handloading complexity far outweighs any accuracy gains that unique-to-each-barrel loads would certainly provide.
At my age, I can use all the simplicity I can muster. I think many of us get hung up on the "Most Accuracy at Any Cost" Mantra, when we neither shoot BR, nor have any practical need for BR type accuracy. I prefer adequate accuracy with the least complexity at a reasonable cost.. We trade knowing stares about group sizes, when all we really need to do is effectively defeat our given target, whatever that actually requires.
The greater proportion of my shooting is 223/5.56 these days (the reasons are obvious), and I handload and shoot several hundred rounds of it per week when the weather is bearable. Right now it is not (mornings are cold and afternoons are windy), and come mid-Summer it won't be (with temps in the mid 100's-to one-teens from 9AM or 10AM on).
The altitudes here run about 4000ft to 4500ft ASL, and distinctions between loads tend to run together a bit more than down in the lowlands. Everything carries velocity further.
I also maintain a fair supply of M-1 Garand .30-'06 M-2 150gr Ball Equivalent ammo loaded in Garand clips. Every charge weight is weighed to a .1gr spec, so I consider it all to be match grade.
I love my Garand and shooting it often is one of the greater joys of my Elder years. So stay off my lawn.... (..er, gravel...)
Greg
