AP ammo is the bullets ONLY, not the loaded ammo, although ATF has identified some AP ammo by the loaded ammo, not projectiles, for the information of FFL dealers, who are not supposed to "willfully" transfer AP ammo.
From this it follows that loading the bullets identified above into
completed rounds does not constitute "making" AP ammo; making the bullets themselves does.
Based on the above, which I found here
http://www 2.cs.cmu.edu/afs/cs/usr/wbardwel/public/nfalist/ap_ammo.txt
you might be ok loading AP bullets.
The ATF refers to "manufacture of armor piercing ammunition" -
here
http://www.atf.treas.gov/firearms/legal/other.htm
"Manufacture or importation of armor piercing ammunition and the sale of such ammunition by manufacturers and importers, 18 U.S.C. 922(a)(7) and (8);"
Does anyone know, is loading ammunition for your own use in your garage defined as "manufacture"?
I'd call them and ask before ordering any of those bullets.