Visual Tutorial on Delayed Blowback Operation -The Firearm Blog
Inside the MP5, the History and Function of Roller-Delay
Blowback (firearms) - Wikipedia
Blowback (firearms) - Wikipedia
What are some mechanical differences between roller-locked and roller- delayed firearms? What parts or mechanisms make it 'delayed' as opposed to 'locked'? - Quora
Scheel MFG Roller-Delayed Buffer System- Complete System
Roller delayed upper from Mean Arms - Pistol Caliber Carbine - Brian Enos's Forums... Maku mozo!
Roller locked - Wikipedia
JP Enterprises JP-5 Roller-Delayed Blowback 9mm Carbines Now Available -The Firearm Blog