Yep, looks like the same issue others have reported. The space above the threads in your atty's 510 connection was not milled out so there's no way you could screw it down flush on your EA 
If I were you I'd look into possibly threading the rest of the connection on your atty. I wonder if there is a die out there for cutting 510 threads, or if 510 threads are a common enough thread that maybe a hardware store would have the cutter you would need...
Sorry I can't be more help, looks like fixing this issue would require a bit of machine work.
If I were you I'd look into possibly threading the rest of the connection on your atty. I wonder if there is a die out there for cutting 510 threads, or if 510 threads are a common enough thread that maybe a hardware store would have the cutter you would need...
Sorry I can't be more help, looks like fixing this issue would require a bit of machine work.