For an AR-15 using a single shot adaptor and 69 -80 grain bullets, what OAL do you use?

0.020" off lands is the baseline. For most 5.56/Wylde that will be about 2.35" with 69/77gr SMK and 2.47" for longer bullets.

ETA: if just going to 600yds, use mag length ammo. Save the effort of single loading 80+gr for beyond.

I am concerned using 25.2 grains of Varget how compressed the load is at magazine length or even the suggested 2.35. Am I overly cautious?

Sorry Rob, using either 69 or 77 TMK.

IMO you are wasting time loading 69 grain bullets longer than magazine length.

The only reason to load 77's long is because you tried 80's and couldn't get them to shoot well. 77's are designed to jump from a magazine.

Normally (that's a really big word) 80's can be loaded around 2.470" in a .223 Wylde chamber, 2.550" in a 5.56mm NATO chamber. I'm talking about Sierra's 80's. Other brands need different settings.

Make double damn sure you can eject the loaded round without pulling the bullet because it is jammed into the rifling. Pressure will spike if you are sticking the bullets hard into the rifling.