25 grains of AA2015 50 grain Bal Tip Shoots extremely well in everything I have tried it in.

My experience is a 1:12 twist should easily stabilize up to a 55-60 gr bullet. At least at our atmospheric in MO/KS.

I forgot to add my barrel is a 1:8 twist. I sincerely appreciate everyone's suggestions. I realize a 223 isn't a "barrel burner" but one other concern I have is Im at least the third owner of this rifle. Honestly I hit what I shoot at in a hunting situation, and maybe I should be content with that, but trying to work up a good load has been frustrating to say the least. Looking to possibly rebarrel. Down the rabbit hole I go.

An 8 twist is for shooting heavy for caliber bullets in a 223.

Try some 65/70/80gr type .224 bullets.

Make sure your barrel is clean. Use a good carbon and copper cleaner. Most people think the barrel is clean, but it isn't.

This^^ I had some 45 gr .224 bullets taht said dont use then in anything faster than a 1 in 9. The spin any faster was to much for them..
Try heavier bullets or solid copper since thaybare longer being lighter than lead. .
And copper fouling is a thing like said above. A ammonia copper cleaner and nylon brush then patches to dry. Repeat until patches come out without the green tint from the copper.

When GM still made Top Engine Cleaner (it is a carbon cleaner), many bench rest shooters added "lab" grade Ammonia to it with a couple other ingredients to clean barrels. It works really well.

The last I heard it might be possible to still find a dealer with some in stock, but it is extremely difficult to find anymore.

my barrel is a 1-8 as well. shoot heavier pills. i use 69grain hpbt matrch ammo and 24 grains or varget and get great results.

I have 223/5.56/223 Wylde twisted 7,8,9,10 and 12, the 8 twist shoots 55 gr better than any of them. Thats reman plain jane vanilla 55 gr. hornady SP's in factory reman ammo. For handloads give IMR 3031 and H335 a go.