It is well known that due to some .223 rifles having too slow barrel rifling twist rates (such as 1:11, or even 1:12) when ammunition having too long, and heavier than average .223 (such as 90 grain, rather than typical 55 grain projectile) can result in key-holing.
The magazines turned win with the LE rifles were lacking all together 6 to 12 rounds from what they would have been had all three 25 round capacity magazines been loaded with 25 rounds, or even 23 rounds.
There's been some mention of persons claiming to have witnessed LEO's picking up a few spent case, without having put those in evidence bags. There was report of even one Hornady case along with the Federal Premium cases. That one Hornady could have been a key-holer, since Hornady does load 90 grain, or even the more commonly encountered 77 grain Sierra Match King in .223/5.56 x 45 Nato rounds -- while as I understand it, in 'Federal' brand, in their so-called "Premium" line (which most of the .223 cases turned in to laboratory for analysis were) does not have anything heavier than 60 grain in .223.
Ref all your “posts”: Time to get off the speed and back on the meds