All of these brown needles seem to me to be normal. Little branch tips die back all the time on evergreens.
Make sure they do not ever dry out too much. That is a good way to go for everything you grow.
Do you fertilize these guys at all? On my property in the past, I have always included fertilizing my evergreens as I fertilize my garden beds. I would fertilize twice a year with Miracle Grow which I think was 10-30-20. It was watered in by using a dispenser on the end of a garden hose. Those were the early April and mid June feedings. My mid May feeding was with Mir Acid which was 30-10-10. Evergreens can use a little extra nitrogen in my opinion.
Good luck.
