Smyth Busters: Large-Caliber ARs Need Heavy Hammer Springs?
This guide addresses the myth that large-caliber AR platforms require heavier hammer springs. Experts Steven and Caleb from Brownells explain that the issue is typically related to primer hardness, not caliber size. Specifically, AR-15s chambered in 7.62x39mm often experience light primer strikes due to hard Russian primers, exacerbated by light aftermarket hammer springs and low-mass firing pins. Solutions involve using heavier power hammer springs, full-mass hammers, and beefier firing pins.













