Any small rifle primer will work for 223/5.56. Military brass case walls are thicker so if you put the same charge in a NATO case as you do in a commercial 223 case your internal pressure will be greater because the internal volume of the case on NATO is smaller. If you are using military brass the crimp in the primer pocket needs to be reamed out before it will fit a commercial Small Rifle primer. I have used all brands except Wolf and had good reults. I have used Small Rifle Magnum primers in 223 loads also but backed off the load 10% to be safe. I would suggest selecting the powder you intend to use load 5 rounds of several different loads going from minimum load to near maxand then test fire each 5 rounds to see which shoot the tighter group, then stick with that load for max accuracy. Here's my last test at the range, roughly 1MOA group-
The 75gr Hornady loads are Skypup's recipe using 25gr BLC-2 powder and Remington 7 1/2 SR primers. Hope this helps you.

The 75gr Hornady loads are Skypup's recipe using 25gr BLC-2 powder and Remington 7 1/2 SR primers. Hope this helps you.