If something is worn at the interface between the hammer and the sear trip on your DIAS, the sear trip is more likely to be the worn part. The sear trip is usually an easily-replaceable sub component of the DIAS, since it is the main body/housing of the DIAS that is the registered part.

If you want expensive -- HERE

And if you want medium priced, here's at least one place:

https://www.bayougunrunner.com/BGR-M16-FULL-AUTO-HAMMER_p_893.html

Best of luck with whatever you pursue.  Be well.

A worn/weak DIAS trip return spring could certainly cause a hammer follow malfunction. The spring needs to not only return the trip to the forward position so it can catch the hammer, it needs to do it quickly while the rifle is firing in cyclic mode. One point of caution though: don’t go any stronger than necessary on that spring, because a strong spring’s extra resistance can cause excessive wear to the trip and/or (much worse!) the registered DIAS body.

On another note, I’ve never seen a worn out M16 hammer. Disconnectors: yes, hammers: no. The stuff that the hammers and triggers are cast from is very durable and they’re very hard. I’m not saying that I’ve seen everything in the world of the M16, but a worn out hammer isn’t one of “the usual suspects” with these rifles.

Apex had colt m16 hammers

Why not replace it with a SSF FCG?