M On my 223 barreled targe varmint gun the chamber is a pretty tight factory originla savage chamber . if i try to shoot 5.56 Nato in it it will blow primers every time . the bullets on the nato are set out further since there heavier thna most 223 loads . this causes a zero fre bore issue an highr pressure . the head space is also a littel but differant but not much I belieave . YOu can shoot 223 in a 5.56 chamber but not he other way around some times . nato has more free bore .
I dont know what barrel those have but its worth mentioning .
since ewe cant see a single decent picutre of the recvier witht he dust cover off we dont realy know whats damaged .
Its abohter one of those posts showing a blown up or broken AK variant with zero proof of cause , zero clue ewhat the ammo really is , zero prrof of what the chamber is . for all we know he slamed a round on top of a already chambered one who knows.
If I was a bettting man Id bet the firing pin was stuck an it slam fired in a out of battery position .
hell we diont even know if the bullet went down the barrel . other than a pick of a damaged mag an a carrer not onthe rails we have no glue if any of its real .