I've been doing quite a bit of research on what .223 round is best for >50 meters. The one thing I kept noticing is almost all the discussions and data I found were 2-6 years old. Is there any optimized round out there now for the shorty set ups?
Did your "quite a bit of research" include the FAQs and the "best choices for defensive ammo" thread?
Just to clarify, you're looking for optimal loads for a short barreled (7.5 inch) AR15 firing at targets greater than 50 yards away?
Quote from Best Choice for Self Defense Ammo
If using a short-barreled weapon: The same guidelines apply as for barrier penetration loads. SBRs usually have insufficient velocity to achieve fragmentation velocity.
As per Doctor Roberts: "Keep in mind, that with non-fragmenting bullet designs, heavier bullet weights are not necessarily better, especially at closer ranges and from shorter barrels. As long as penetration and upset remain adequate, it is possible to use lighter weight non-fragmenting bullets and still have outstanding terminal performance. With fragmenting designs, a heavier bullet is ideal, as it provides more potential fragments and still allows the central core to have enough mass for adequate penetration. In addition, heavier bullets may have an advantage at longer ranges due to better BC and less wind drift."