[bones0831]

Why are there +/- sizes for HK rollers, such as 8mm, then -.02 7.98mm rollers. I know different roller sizes would interact with the LP differently, changing the speed that the bolt would cycle, but what is the purpose of this? I am trying to keep spare rollers on hand for my SP 89 and HK 93 (both factory HK), but what size spares should I keep on hand, and is there a need to keep a oversize or undersize on hand? Lastly, do all size rollers take the same retaining pin/plate?

 

[Chopstix Kid]

Rollers are a service item to adjust for too little or too much bolt-gap. DO NOT use them to attempt to change the ROF of your firearm.