1. Material
a. Steel: Full auto
b. Titanium (~no full-auto)
c. Hybrid (9mm to .300 Win Mag)
2. Weight
3. Length
4. Barrel Length Restriction
5. Size: Diameter/circumference
6. Decibel Reduction
a. At the ejection port
b. At the Shooter’s ear
c. First Round Pop
d. Subsequent rounds
7. Tone at the Shooter’s Ear
8. Bystanders perception
a. Boomy / harshness
9. Flash Signature Reduction
10. Blowback
11. Mounting: Direct thread / Quick-detach
a. Options for Quick Detach
Adapters
b. Universal Quick Detach Adapters
12. End Caps
13. Manufacturer’s Quality Control / Demonstrated Manufacturer Quality
14. Customer or Factory Serviceability
15. Customer Service from Manufacturer
16. Manufacturer’s Viability
17. Warranty
18. Price
Variables
- Caliber
- Barrel length
- Ammo grain (supersonic vs. subsonic)
- Bolt action vs. direct impingement
- Hearing loss for shooter and bystanders