Blackfork is trying to develop subsonic loads for his .223:
I looked on the Hogden site and found a subsonic load: 3.1 grains of Titegroup and a 55 grain bullet. I tried 3.1 grains of Titegroup under a Nosler 69. It works, doesn’t cycle the rifle but it’s quiet. The gun kind of rattles a bit when it goes off. Kind of a beefed up .22lr. About six inches under the zero for my normal ammo.
As he said, a problem is that a subsonic 55 grain has about the same muzzle energy as a High velocity .22 Long Rifle. On the other hand a heavy 77 grain bullet will not give great accuracy unless the correct barrel twist is used. The Shooting Times says a 1:8 twist rate is the minimum need to stabilize a 77 grain Sierra MatchKing.
I look forward to following BlackFork’s progress.
More at BlackFork
Hat Tip: Snowflakes in Hell