Hello, UncleGrumpy. I am sorry I can't help on your Ackley Hornet...However, I do have an Ackley .22 Bee. I have this chambered in a Shillen barreled customized Australian cadet. Now when the chamber reamer arrived from Pacific Tool, I didn't care for the short neck..thinking of possibility of shooting cast bullets in future. So I had them push neck back to original Win. .218 bee length.
I headspace off case rim, I use start loads for std. .Win. 218 Bee.
I am confused about your thinking of throwing away brass after only 3 shots. I have a std. .22 Hornet..which "everyone" knows eats brass alive..what with that 5 deg. shoulder..this is in an original Sharps-Borchardt action. Shillen chambered this one with minimum dimensions & very tight headspace (asked Ed to build as if it were a bench-rest gun). I am still using same RWS Hornet brass now for over 10 years. If action locks up tight..& chambered close..and you don't "hot-rod" it..those cases should last a very long time.