I bought some Slick Trick broadheads to try. They will not screw into the ferrules on my arrows. Are they a different thread size? Is there a thread adapter I should be using?

What arrows

To my knowledge, there’s only 2 types of ferrules and inserts-standard and deep 6. The 2 are not interchangable and I’m assuming that’s the issue here.

The industry standard is an 8-32 thread. The only exception is the Easton Deep 6. You can get adapters to shoot normal sized heads with those.

Yup, this is very likely the issue.

I have it figured out. The threads on the first one out of the package were cut wrong. The other three in the package thread on just fine. I'll run a thread chaser on the bad one and see if I can clean up the threads. Thanks for everyone's help.