First, you've asked several times for OAL.
You will find out, that the ideal COAL will be decided by your boolit and your Rifle...and if you are using PC, that'll add to the formula...So we can't give you a COAL. I believe I used a 0.010" jump to the lands, so I'd have reliable chambering and reliable ejection of a unfired round.
To successfully get a AR to cycle ammo (and be accurate), you need a slower burning powder that can be downloaded. From what I've read, one real good powder is H4895. Hodgdon says you can download it to 60% of their MAX load. It should be said that, IMR4895 is not the same, although they are similar, I don't think Dupont recommends the 60% download thing.
Here are some notes from my initial testing. You will need to do similar testing with your rifle, as it is a different rifle and you will get different results. Once you know what cycles your gun, you can continue with the usual ladder testing to find the most accurate load for your Boolit and your Rifle. You will probably find that the window is quite narrow for good accuracy. Good Luck
More info:Using the 62gr HM˛ (.226/SL68B) loaded with H4895 for 556 AR (1:9).
This was just a test to see what cycles the action.
I loaded about 6 rds of each. 18gr. 19gr. 20gr. 21gr.
the 18gr didn't eject the brass
the 19gr ejected the brass, but didn't cycle a new round into the chamber...except the last round, which jammed.
the 20gr cycled as it should, but seemed slow, like a howitzer.
the 21gr cycled perfectly.
This is a brand new DPMS gun, so spring and action may be stiff.
I was shooting off-hand at 25 yards in the pistol pit, all 6 rd groups were 1 to 1.5" with a couple called fliers. so, not a good test of accuracy, but I've seen lots worse in other guns when boolit was poorly matched to load and/or gun.
http://castboolits.gunloads.com/show...load-data-help
Want more info, type "AR cast" into google custom search box.