Modding Breech Plug

[7shortmag]

I was rooting through my blackpowder stuff and found a caplock breech plug that I forgot I had.
As mentioned in another thread, I am re-barreling my T/C Renegade Flintlock, I will need a breech plug.
Is it possible to machine this caplock breech plug and make it work for a flintlock?

 

[Grenadier1758]

The first question that must be asked is "Once we are done will the rifle be safe to fire?" You have not provided enough information to answer that question.

What are the threads in your rifle?
What are the threads on your breech plug?
What is the size and shape of your breech plug?

Since we don't know these things I can't recommend that you proceed with the modification.