Head space and pressure,

you can feed .223s in a barrel chambered in 5.56 all day long,

but the working psi of the 5.56 exceeds the working psi of the .223 barrel, plus the forced infacement of the 5.56 cause the psi to spike even higher, if I recall +/- 40k psi.

Problem waiting to happen.

Head space and pressure,

you can feed .223s in a barrel chambered in 5.56 all day long,

but the working psi of the 5.56 exceeds the working psi of the .223 barrel, plus the forced infacement or the 5.56 cause the psi to spike even higher, if I recall +/- 40k psi.

Problem waiting to happen.