https://www.accurateshooter.com/cartridge-guides/223rem/
It will be tough to beat Varget under an SMK 69 or 77.
Spherical powders are known for their ease of use through powder drops in progressive presses. Don't get me wrong, their accuracy is good, but there is a reason folks still prefer an extruded powder with temperature stability being a good reason. Ball powders do okay, but they are not the equivalent of the extruded powders.
I run H335 and CFE223, but I use it for bulk loading prairie dog ammo where the focus is usually under 450 yards in 40 grain VMax loads. I have to anticipate and compensate those for the temp swings I get in prairie dog country during the summer.
The Sierra 69 and 77 SMK and TMK are more along the lines of XTC ammo at mag length for the 200, 300 yard lines. Most folks single feed a SMK 80 for the 600 yard line.
Part way down the page on that link, you will see the Sierra Manual pages, one for bolt and one for AR. In addition to Varget, N140, RE-15 and ARComp are popular and have been around for a long time.
Not sure why you were not happy with Varget, but could it be expectations are different?
Tell us what you loaded and maybe a little about your process and results. You may be just fine, or you may be off someplace, but there is a whole world of load recipes out there for 223/556 and that may not be helpful.
