The BCM Railed Upper has a Ballistic Advantage 5.56x45 4150 crmov s1325 barrel with a 1:7 Twist
The PSA Railed Upper is a .223 Wylde USA Barrel with a 1:8 Twist
I personally have never shot anything out of these, the BCM one is new and I believe the 223 Wylde has less than 100 rounds through it.