It implies that sizing your cases a bit too much is very unlikely to be the cause of your misfires. Your firing pin will reach the primer of even the most freakishly short cartridges and then some. The comment about the field gauge is pointing out that even a rifle with dangerous head space still goes bang.
Primer misfires are easy. Either they are junk , which occasionally happens, the reloader made them into junk, or they aren't getting hit hard enough.
Savages are famous for light strikes. (So
is Kimber) There's a reason why Wolf makes 36
pound springs for them. CCI are known for hard primers. Guys use them
for masking pressure signs all the time. Light strike meets hard primer and misfires result. It still fires most of them
which just shows how fine the line between almost working and barely working is.
Rip your bolt apart and clean it. Chances are it has the original sticky packing grease and some grime by now. Give it a chance to hit as hard as it can. Doesn't cost anything.
If that doesn't work, try some Federal primers. They are the softest thing around, and don't need to
be hit so hard. Besides, your rifle has already shown it will fire those in factory guise.
If that doesn't work get a new striker spring, or an extra strength spring if they exist for your rifle. A spring costs about the same as a couple boxes of primers and anyone can make a dud.