I know the question always asked is why? Like that stops anybody in this forum in their strange quests for stuff nobody else wants. I know 22lr does pretty much the same job, but I cant shoot 22lr thru my 5.56 bolt gun. And it will be going thru a can. You can also get more weight in a 223.
I messed with it before but always got such garbage results. Either really low velocity where I risked them stuck in the barrel or accuracy killing wide swings in velocity. I tried the usual recipes found on the web: trailboss, titegroup or bullseye. I had extreme spreads w trailboss of 220fps. Needless to say that was not going to work. W a 1-9 twist barrel, 60gr flatbase is about as heavy as I can go with a jacketed bullet. Boat tailed anything wont really work. They sell a hollow point 45gr for the 218 bee that looks like it would work pretty well, but they dont make them heavier.
Only mold I have is the lyman 55gr. It works in my bolt gun, not terribly accurate. I want them to fit in the magazine, which makes them a bit short for best accuracy w that bullet. But I can get them to work without the large swings in velocity. I used solo 1000 that I have been using in all my other subsonic ammo. And drilled the flashholes out, maybe not critical in larger calibers. But sure seems to be important in the 223. 2.5gr of S1000 got me 1019fps w the 55gr and ES of only 11fps. I used some 60gr SP jacketed I had, 3.5gr of S1000 got me avg 1017fps, w ES of 64.43 fps. Not exactly terrible. Pretty dang accurate.
What I am looking for is a heavier mold. That 60gr SP thats stable is .755 long. So any cast the same length should work. NOE has a 70gr RN, anybody ever use it?
Powder coated would imagine it can be driven full velocity if needed.