could be that his 16 is not set up with the right friction rings for high brass loads.
This can cause the bolt to slam the reciever with less recoil being absorbed by the spring.
For heavy loads-put both rings to front,
bronze piece toward barrel lug, then friction ring behind with beveled edge next to bronze.
for light loads- move the friction ringto other end of spring, beveled edge toward reciever(flat side to spring)
I leave my old A5s set up for heavy loads and only change them if they fail to cycle properly.
Hope this helps