Open base FMJ swaged bullets are harder to make than the usual open tip swaged bullet due to the way they are formed by the various dies. A good read on the subject http://www.shootingtimes.com/2011/01/04/ammunition_st_223short_200711/
WHAT FEDERAL RESTRICTIONS ARE PLACED ON AP AMMO?
If you are NOT a (FFL) licensee under the Gun Control Act (an individual):
It is: ok to OWN AP ammo
ok to SELL AP ammo
ok to BUY AP ammo
ok to SHOOT AP ammo
NOT ok to MAKE AP ammo (18 USC sec. 922(a)(7))
NOT ok to IMPORT AP ammo (18 USC sec. 922(a)(7))
The only persons who can make AP ammo are holders of a type 10
FFL, also needed to make destructive devices, and ammunition for
destructive devices. The only persons who can import AP ammo
are holders of a type 11 FFL, who can also import DD's and ammo
for DD's. The FFL's cost $1000 a year.