It's been ~1k rounds since i last cleaned my glock. there is a hard buildup on the barrel - feed ramp and upper right corner. I've gotten most of it off with a toothbrush with clp but some still remains. is there an easier way to get it off? on pg37 of the glock manual, section titled "lubricating the field stripped pistol" it says "most important, a drop of oil is needed where the rear end of the trigger bar touches the connector at the right rear corner of the frame" Is there a closeup pic available pointing out that area?