Good evening fellas....and ladies! I came across an AR Sales Mark IV and I was looking for some information on them. This was the first place I was able to find anything so here I am! Great information Different, thank you! My uncle was part of Walker Machine Co. down in California and when I saw his rifle I wanted to do some research on it being that the only M1A I knew of was the ones we carried in Iraq. Anyway, this seems like a good place to get plugged in. Any input would be great.