I'm at 25.3 grains. The Hodgdon data is weak, but my lyman 49th (too hot) shows somewhere above 27grains, while I was finding the best results at 26.2. I had a few head separations, and found a new best results (25.3). I know someone who had 2 flashovers using 19 grains, so the hodgdon starting load makes me nervous. the first blew out the casehead, ballooned the magazine. Thinking it was an out of battery, he shot more and eventually did the same on another rifle. Thanks to the powder shortage, we know he was using rifle powder, its the only kind he had. It was not an overcharge either, you can't accidentally fit enough H335 in a case to KB a bolt gun in one shot. In addition, I can't imagine any pistol powder that would not have blown out far more than the bolthead with 19 grains in a .223.
I know the validity of flashover is debated and I won't argue on another persons behalf, but going too low does cause squibs, and I have recently experienced 2 squibs using published data, for a less than ideal powder, in a caliber I don't load enough to justify buying its own. Again, published loads.
The most common universal load I have seen is 25 grain, which will run reliable in everything, and needs only slight adjustment for accuracy. My favorite source for load data is Lyman 49th, and for unusual combos, Speer has some good info, published on the internet, including Alliant 2400 for .300 AAC. If thats somethig anytone heres looking for .
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https://reloading-data.speer-ammo.c...Rifle/22_caliber_224_dia/223_Remington_55.pdf