The break-in period is just something some makers use to avoid having people call them up right away and say "my gun jammed. it there's something wrong with it. will you fix it for free?"
After 100 rounds a gun is broken in. If there is going to be a major issue it has already reared it's head.
I like to break a gun in like I would a varmint rifle. Shoot one round, let it cool, clean it, shoot another. I do that for the first 10 rounds. Then I I fire one full mag, slow fire. Let it cool and clean it.
At that point, if there are no issues, I fire a mag rapid fire at multiple targets, changing target with every round.
If no issues, I double tap at a multiple targets, changing targets after every double tap.
Clean.
Then shoot 100 rounds any way I feel like it. If it has not yet malfunctioned it is very unlikely it will malfunction under normal circumstances.
If, at any point, it malfunctions, I put it away and take it home to analyze the type of failure.
Assuming you properly cleaned and lubed the gun before firing, 90 percent of failures are spring issues. The remaining 10 percent are evenly divided between extractor and machining problems.
Generally machining problems are visible.
The unknown here is ammo. Handloaded ammo can cause a lot of problems when it is poorly done.
OTOH, some types of factory ammo are just plain crap and can cause the finest gun to appear to be junk.
Bottom line is: it's a gun, shoot it; if it doesn't work - fix it.