I sold a Blue Label Match HBAR which has a sear block in it to a gentleman.  He wants to have the sear block removed but his neighbor says that he can't legally do it.  I was of the understanding that it is not illegal to remove the sear block and that I was given either a quote from BATF regulations or a copy of correspondence from BATF which stated that, but I can't put my hands on it.  If I am correct in this, would someone shoot me a copy of BATF's thoughts on the matter.  I also remember receiving email from a gunsmith that will remove the sear block for a charge.  If he is reading this, or if someone can give me the name of a competent gunsmith that does this work, assuming there again that it is legal to do such, I would appreciate it so that I might notify the buyer of my gun.  I apologize if someone is reading this from an earlier post, but I'm getting absent minded in my old age.

I don't have the exact link, but you are correct. It is perfectly legal to remove the sear block. The sear block is simply an extra measure to remain PC. There is no legal necessity for it. It just makes it harder for someone to illegally convert to full auto.

Thanks to everyone for the information.  I forwarded this to the new owner along with the name of a gun smith that was provided.  Also bookmarked the information so when I'm asked again, I won't have to bother ya'll again.  Many thanks !!  

Just curious, does your buyer have a DIAS?  Or does he just want to mill out the sear block for the sake of doing so?

The buyer doesn't have a DIAS.  I think that he is just curious about the legalities of removing the block and is not fully aware of what exactly is involved in the rest of the process.