If factory ammo, federal fusion 62 grain or gold dot in 62 or 75gr. These are bonded bullets, they expand well and penetrate deep.
If loading your own, you can purchase the 62gr gold dot as a component. I use a 223 Wylde chamber, and load them to speers 5.56x45mm load data. Cfe223 27.2gr gets me 3100fps from my white oak 18in spr barrel, and 3 quarter inch groups at a hundred yards.
As a side note, I also load the 62gr gold dot for my 10.5in AR pistol. 26.7gr TAC gets me 2700fps. Both loads use a CCI 41 primer.
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