Getting back into reloading.

I'm getting back into reloading and have gotten most of my gear unpacked and my "gun room" set up and organized. I have about three pounds of various powders and about 2,000 primers. They are about 4 years old and always kept in my house in climate-controlled settings. Are they still safe to use?

yes, I would load them.

If they had gotten wet it would be a problem. Otherwise no problem.

I have some 50 year old rifle primers that work just fine with identical results from when they were brand new.
I've also shot up thousands of rounds of 1904 and earlier rifle cartridges.
And so it goes...

Those primers should work. I was given a 1000 CCI small rifle primers by a local shop. The were wet [water] when received. The company replaced them but wouldn't take the wet ones back. He gave a 1000 pack to me. I fired them all in a 223 bolt rifle with no problem so I'm sure yours will work fine.

There's some powders and primers that old that have been sitting on LGS shelves. Load and shoot! Like others have/will mention, I have powder and primers mebbe 20+ years old and still in good shape...

I still have some old Remington primers that came in little wooden trays from the late 50s. They still work.

The large rifle primers I'm still using were purchased in 1994.

I have shot ww2 4831 powder recently that still shoots fine.