From what you have said I am going to suggest you check each cartridge you load before the cartridge gets a bullet placed upon it. If 4.7 gr will cycle your gun so will 4.6. But if some cycle and some don't it almost sounds like you are getting inconsistent powder charges. A Chrony would answer that question for the cartridges you already have loaded. Not being there to witness the shots or being able to run them over a Chronograph makes it difficult to determine the cause. The one thing we do know it isn't the gun.
Take Care
Bob
Take Care
Bob
