Anything is possible, you could have some that was stored poorly.
However, that dud rate goes against my experience and that of anyone I know of.
This is the truth of it. It's not the age or maker, as much as it is the storage conditions. Thousands of rounds of czech stuff, some dating back to the sixties, and it all went bang. I have a stack of hungarian heavy ball x 54r that is "prone to misfire and hangfire" according to 7.62x54r. net that also all went bang. Go figure. Mine was kept dry and cool, theirs was damp and hot.
Country of manufacture probably tells you a bit. When I think .303 made in India, I think of a humid cave in the basement of some old fort with crates of the stuff. Stands to reason that it might be a little iffy...


















































