Thousands, actually. I'll name a few for you:
- A1 and variants
- A2 and variants
- M4 and variants
- Slab-Side A1 and variants
- M4 sub-guns - at least 50 of these
- Pistol variants of all of the above
- Sporter Carbine
- HBAR configuration (with/without bayo lug)
- SBR variants of all of the above
- Nearly every common caliber, including 12-gauge and 50 BMG in various AR-variants
- Tri-burst variants
- DIAS configured variants
- Billet Receiver variants with commercial tubes
- Billet Receiver variants with Milspec tubes
- Folding stock variants
- Gas Piston variants
- Russian ADAR
- Dawoo AR-100
I'm bored. That's enough - - and this is just from memory.