Lurker.....
I agree that the accuracy of the tool is a big consideration. I did a lot of reading various threads across the web and found some negative comments on the units at Brownells and Midway. I found another source that seems to put out a high quality lapping tool.
I ordered one yesterday.
http://shop.pacifictoolandgauge.com/inde...roducts_id=1139
There is another style squaring tool I found at Brownells but it's more expensive and looks a little "aggressive" to me:
http://www.brownells.com/.aspx/pid=20449/Product/RECEIVER-FACING-CUTTER-PILOTS
