Threading problem

[Zamble]

I drilled both holes in a Razor 10/22 80% for the screws for the v-block. I threaded one side no problem. I started threading the other side and it went in about 2 turns. So it is in, but just a little beyond barely. Then the tap broke.

How can I extract the broken tap?

[ar15barrels]

If you drilled the holes all the way through that wall and into the receiver cavity, knock out the broken tap piece from the inside out.

[Zamble]

I tried for inside to the outside, all I have to show for it is a bent rod. I found some Broken tap tool, but I am unsure of the size I need. I used a 12-24 NC tap. The company is Walton.