[Spots]

If its marked. 223 only I wouldn't shoot 5.56 on it. There is a lot of reading on google about this.

Sent from behind my anvil in ye olde smithy

 

[Spots]

If I'm not mistaken, the receiver stamp should say "CAL .223" (at least that's what is on my 186-series) which is not the same as .223 Rem, it's just indicating the caliber of bullet in the rifle. Ruger states that the only Mini-14 not meant to fire 5.56 NATO is their Target Model, all the others have a receiver that is actually sized more to the 5.56 than it is the commercial .223 Rem

This will make all the difference. If its marked caliber 223 then 5.56 should be fine. But if it is chambered specifically in .223 remington, there is a difference